The Third National Health and Nutrition Examination Survey (NHANES III), 1988-94, Series 11, No. 8A Data Release. The National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention (CDC) collects, analyzes, and disseminates data on the health status of U.S. residents. The results of surveys, analyses, and studies are made known through a number of data release mechanisms including publications, mainframe computer data files, CD-ROMs (Search and Retrieval Software, Statistical Export and Tabulation System (SETS)), and the Internet. The National Health and Nutrition Examination Survey (NHANES) is a periodic survey conducted by NCHS. The third National Health and Nutrition Examination Survey (NHANES III), conducted from 1988 through 1994, was the seventh in a series of these surveys based on a complex, multi-stage sample plan. It was designed to provide national estimates of the health and nutritional status of the United States' civilian, noninstitutionalized population aged two months and older. This data release, Series 11 No. 8A, includes NHANES data and data prepared by the Division of Vital Statistics, NCHS. Since 1985, natality statistics for all States, the District of Columbia, U.S. Virgin Islands, Puerto Rico, and Guam have been based on information from the total file of birth records. The information is received on computer data tapes coded by the States and provided to NCHS through the Vital Statistics Cooperative Program. Series 11 No. 8A includes Natality data for births occurring within the United States to residents and nonresidents. Of the 8,836 children 2 months through 6 years of age from whom interview data were obtained in NHANES III, 7779 have linked birth certificates from the NCHS Division of Vital Statistics. Births occurring to US citizens outside the US are not included in this file. This data release does not replace the previous NHANES III data release. Background information on the procedures, survey components, questionnaires, examination and laboratory methods, and statistical analysis guidelines is available on the NHANES III Reference Manuals and Reports (CD-ROM). All data users are strongly encouraged to review these reference materials and reports before analyzing NHANES III data. Guidelines for Data Users o NHANES III survey design and demographic variables are found on the Household Adult Data File, Household Youth Data File, the Laboratory Data File and the Examination Data File. In preparing a data set for analysis, other data files should be merged with either or both of the Adult Household Data File or the Youth Household Data File to obtain many important analytic variables. o All of the NHANES III public use data files are linked with the common survey participant identification number (SEQN). Merging information from multiple NHANES III data files using this variable ensures that the appropriate information for each survey participant is linked correctly. o NHANES III public use data files do not have the same number of records on each file. The Household Questionnaire Files (divided into two files, Adult and Youth) contain more records than the Examination Data File because not everyone who was interviewed completed the examination. The Laboratory Data File contains data only for persons aged one year and older. The Individual Foods Data File based on the dietary recall, the Prescription Medication Data File, and The Vitamin and Minerals Data File all have multiple records for each person rather than the one record per sample person contained in the other data files. o For each data file, SAS program code with standard variable names and labels is provided as separate text files on the CD-ROM that contains the data files. This SAS program code can be used to create a SAS data set from the data file. o Modifications were made to items in the questionnaires, laboratory, and examination components over the course of the survey; as a result, data may not be available for certain variables for the full six years. In addition, variables may differ by phase since some changes were implemented between phases. Users are encouraged to read the Notes sections of the file documentation carefully for information about changes. o Extremely high and low values have been verified whenever possible, and numerous consistency checks have been performed. Nonetheless, users should examine the range and frequency of values before analyzing data. o Some data were not ready for release at the time of this publication due to continued processing of the data or analysis of laboratory specimens. A listing of those data are available in the general information section of each data file. o Confidential and administrative data are not available or released to the public. Additionally, some variables have been recoded to protect the confidentiality of the survey participants. For example, all age-related variables were recoded to 90+ years for persons who were 90 years of age or older. o Some variable names may differ from those used in the Phase 1 NHANES III Provisional Data Release and some variables included in the Phase 1 provisional release may not appear on these files. Do not use the Phase 1 provisional release; use the current (six-year) release. o Although the data files have been edited carefully, it is possible that errors may still exist. Please notify NCHS staff (301-458-4636) of any suspected errors in the data file or the documentation. Refer to the NCHS website at http://www.cdc.gov/nchs/nhanes.htm for updates to these data files. Analytic Considerations o NHANES III (1988-94) was designed so that the survey's first three years, 1988-91, its last three years, 1991-94, and the entire six years were national probability samples. Analysts are encouraged to use all six years of survey results. o Sample weights are available for analyzing NHANES III data. One of the following three sample weights will be appropriate for nearly all analyses: interviewed sample final weight (WTPFQX6), examined sample final weight (WTPFEX6), and mobile examination center (MEC)- and home-examined sample final weight (WTPFHX6). Choosing which of these sample weights to use in any analysis depends on the variables being used. A good rule of thumb is to use "the least common denominator" approach. In this approach, the user checks the variables of interest. The variable that was collected on the smallest number of persons is the "least common denominator," and the sample weight that applies to that variable is the appropriate one to use for that analysis. For more detailed information, see the Analytic and Reporting Guidelines for NHANES III (U.S. DHHS, 1996). Referencing or Citing NHANES III Data o In publications, please acknowledge NCHS as the original data source. For instance, the reference for the NHANES III Examination Data File on this release: U.S. Department of Health and Human Services (DHHS). National Center for Health Statistics. Third National Health and Nutrition Examination Survey, 1988-1994, NHANES III Natality Data File (Series 11, No. 8A). Hyattsville, MD: Centers for Disease Control and Prevention, 1999. Using the files from this Data Release Your analysis software should be able to read data files from this release after the extraction from the "zipped" file named Natal.EXE. In order to extract the data files, documentation and SAS code please follow these steps: o Copy this file to an appropriate directory or folder on your hard-drive. o If you are using a PC compatible computer, double-click on the file from within Windows Explorer (not Internet Explorer). This will extract all of the necessary files into the directory or folder you have chosen. The documentation files is named natal.doc. The SAS programs to convert the flat files into SAS format are named natal.SAS. The ASCII data files is named natal.DAT. To access a documentation file open it in a word processor, set the margins to zero and the font to Courier 12 point. View or print any pages needed. Some of these documents are hundreds of pages long. For SAS users, open the SAS program for the data set required into Program Manager. Change the FILENAME statement as needed for the operating system (the supplied FILENAME assumes DOS conventions where the hard-drive is C:\). To create a permanent SAS data set, modify your data step statement as required by your operating system. If space is limited, consider adding a KEEP statement to specify the variables of interest. The data files may be used in other analysis packages by using the field positions found in the index portion of the corresponding documentation. Problems Using the Data NHANES III is a wonderfully rich source of data and NCHS encourages you to use the data for research and analysis. However, the dataset is large and complex and familiarity with data file manipulation and analysis is required. NCHS does not have the personnel resources to perform analyses, check results, debug programs or do literature review for your work. Thorough review of the extensive documentation on the planning of the survey, analytic guidelines and individual datasets should resolve most questions. If you still have questions after careful review of the documentation, please contact the Data Dissemination Branch at (301)458-4636. NHANES III Examination Data File Index ------------------------------------------------------------------------ Variable Description Name Positions ------------------------------------------------------------------------ GENERAL INFORMATION Sample Person identification number ......... SEQN 1-5 Family sequence number ...................... DMPFSEQ 6-10 Examination/interview status ................ DMPSTAT 11 Race-ethnicity .............................. DMARETHN 12 Race ........................................ DMARACER 13 Ethnicity ................................... DMAETHNR 14 Sex ......................................... HSSEX 15 Date of screener: month ..................... HSDOIMO 16-17 Age at interview (screener) - qty ........... HSAGEIR 18-19 Age at interview (screener) - unit .......... HSAGEU 20 Age in months at interview (screener) ....... HSAITMOR 21-24 Age at exam - in days ....................... MXPAXTDR 25-28 Family size (persons in family) ............. HSFSIZER 29-30 Household size (persons in dwelling) ........ HSHSIZER 31-32 Rural/urban code based on USDA code ......... DMPMETRO 33 Census region ............................... DMPCREGN 34 Poverty Income Ratio (unimputed income) ..... DMPPIR 35-40 Phase of NHANES III Survey .................. SDPPHASE 41 Total NHANES III pseudo-PSU ................. SDPPSU6 42 Total NHANES III pseudo-stratum ............. SDPSTRA6 43-44 Pseudo-PSU for phase 1 ...................... SDPPSU1 45 Pseudo-stratum for phase 1 .................. SDPSTRA1 46-47 Pseudo-PSU for phase 2 ...................... SDPPSU2 48 Pseudo-stratum for phase 2 .................. SDPSTRA2 49-50 Total interviewed sample final weight ....... WTPFQX6 51-58 Total MEC examined sample final weight ...... WTPFEX6 59-66 Total M+H examined sample final weight ...... WTPFHX6 67-74 Total allergy subsample final weight ........ WTPFALG6 75-82 Phase 1 interviewed sample final wgt ........ WTPFQX1 83-91 Phase 1 MEC examined sample final wgt ....... WTPFEX1 92-100 Phase 1 M+H examined sample final wgt ....... WTPFHX1 101-109 Phase 1 allergy subsample final wgt ......... WTPFALG1 110-118 Phase 2 interviewed sample final wgt ........ WTPFQX2 119-127 Phase 2 M+H examined sample final wgt ....... WTPFHX2 128-136 Phase 2 MEC examined sample final wgt ....... WTPFEX2 137-145 Phase 2 allergy subsample final wgt ......... WTPFALG2 146-154 Replicate 1 final interview weight .......... WTPQRP1 155-162 Replicate 2 final interview weight .......... WTPQRP2 163-170 Replicate 3 final interview weight .......... WTPQRP3 171-178 Replicate 4 final interview weight .......... WTPQRP4 179-186 Replicate 5 final interview weight .......... WTPQRP5 187-194 Replicate 6 final interview weight .......... WTPQRP6 195-202 Replicate 7 final interview weight .......... WTPQRP7 203-210 Replicate 8 final interview weight .......... WTPQRP8 211-218 Replicate 9 final interview weight .......... WTPQRP9 219-226 Replicate 10 final interview weight ......... WTPQRP10 227-234 Replicate 11 final interview weight ......... WTPQRP11 235-242 Replicate 12 final interview weight ......... WTPQRP12 243-250 Replicate 13 final interview weight ......... WTPQRP13 251-258 Replicate 14 final interview weight ......... WTPQRP14 259-266 Replicate 15 final interview weight ......... WTPQRP15 267-274 Replicate 16 final interview weight ......... WTPQRP16 275-282 Replicate 17 final interview weight ......... WTPQRP17 283-290 Replicate 18 final interview weight ......... WTPQRP18 291-298 Replicate 19 final interview weight ......... WTPQRP19 299-306 Replicate 20 final interview weight ......... WTPQRP20 307-314 Replicate 21 final interview weight ......... WTPQRP21 315-322 Replicate 22 final interview weight ......... WTPQRP22 323-330 Replicate 23 final interview weight ......... WTPQRP23 331-338 Replicate 24 final interview weight ......... WTPQRP24 339-346 Replicate 25 final interview weight ......... WTPQRP25 347-354 Replicate 26 final interview weight ......... WTPQRP26 355-362 Replicate 27 final interview weight ......... WTPQRP27 363-370 Replicate 28 final interview weight ......... WTPQRP28 371-378 Replicate 29 final interview weight ......... WTPQRP29 379-386 Replicate 30 final interview weight ......... WTPQRP30 387-394 Replicate 31 final interview weight ......... WTPQRP31 395-402 Replicate 32 final interview weight ......... WTPQRP32 403-410 Replicate 33 final interview weight ......... WTPQRP33 411-418 Replicate 34 final interview weight ......... WTPQRP34 419-426 Replicate 35 final interview weight ......... WTPQRP35 427-434 Replicate 36 final interview weight ......... WTPQRP36 435-442 Replicate 37 final interview weight ......... WTPQRP37 443-450 Replicate 38 final interview weight ......... WTPQRP38 451-458 Replicate 39 final interview weight ......... WTPQRP39 459-466 Replicate 40 final interview weight ......... WTPQRP40 467-474 Replicate 41 final interview weight ......... WTPQRP41 475-482 Replicate 42 final interview weight ......... WTPQRP42 483-490 Replicate 43 final interview weight ......... WTPQRP43 491-498 Replicate 44 final interview weight ......... WTPQRP44 499-506 Replicate 45 final interview weight ......... WTPQRP45 507-514 Replicate 46 final interview weight ......... WTPQRP46 515-522 Replicate 47 final interview weight ......... WTPQRP47 523-530 Replicate 48 final interview weight ......... WTPQRP48 531-538 Replicate 49 final interview weight ......... WTPQRP49 539-546 Replicate 50 final interview weight ......... WTPQRP50 547-554 Replicate 51 final interview weight ......... WTPQRP51 555-562 Replicate 52 final interview weight ......... WTPQRP52 563-570 Replicate 1 final exam weight ............... WTPXRP1 571-578 Replicate 2 final exam weight ............... WTPXRP2 579-586 Replicate 3 final exam weight ............... WTPXRP3 587-594 Replicate 4 final exam weight ............... WTPXRP4 595-602 Replicate 5 final exam weight ............... WTPXRP5 603-610 Replicate 6 final exam weight ............... WTPXRP6 611-618 Replicate 7 final exam weight ............... WTPXRP7 619-626 Replicate 8 final exam weight ............... WTPXRP8 627-634 Replicate 9 final exam weight ............... WTPXRP9 635-642 Replicate 10 final exam weight .............. WTPXRP10 643-650 Replicate 11 final exam weight .............. WTPXRP11 651-658 Replicate 12 final exam weight .............. WTPXRP12 659-666 Replicate 13 final exam weight .............. WTPXRP13 667-674 Replicate 14 final exam weight .............. WTPXRP14 675-682 Replicate 15 final exam weight .............. WTPXRP15 683-690 Replicate 16 final exam weight .............. WTPXRP16 691-698 Replicate 17 final exam weight .............. WTPXRP17 699-706 Replicate 18 final exam weight .............. WTPXRP18 707-714 Replicate 19 final exam weight .............. WTPXRP19 715-722 Replicate 20 final exam weight .............. WTPXRP20 723-730 Replicate 21 final exam weight .............. WTPXRP21 731-738 Replicate 22 final exam weight .............. WTPXRP22 739-746 Replicate 23 final exam weight .............. WTPXRP23 747-754 Replicate 24 final exam weight .............. WTPXRP24 755-762 Replicate 25 final exam weight .............. WTPXRP25 763-770 Replicate 26 final exam weight .............. WTPXRP26 771-778 Replicate 27 final exam weight .............. WTPXRP27 779-786 Replicate 28 final exam weight .............. WTPXRP28 787-794 Replicate 29 final exam weight .............. WTPXRP29 795-802 Replicate 30 final exam weight .............. WTPXRP30 803-810 Replicate 31 final exam weight .............. WTPXRP31 811-818 Replicate 32 final exam weight .............. WTPXRP32 819-826 Replicate 33 final exam weight .............. WTPXRP33 827-834 Replicate 34 final exam weight .............. WTPXRP34 835-842 Replicate 35 final exam weight .............. WTPXRP35 843-850 Replicate 36 final exam weight .............. WTPXRP36 851-858 Replicate 37 final exam weight .............. WTPXRP37 859-866 Replicate 38 final exam weight .............. WTPXRP38 867-874 Replicate 39 final exam weight .............. WTPXRP39 875-882 Replicate 40 final exam weight .............. WTPXRP40 883-890 Replicate 41 final exam weight .............. WTPXRP41 891-898 Replicate 42 final exam weight .............. WTPXRP42 899-906 Replicate 43 final exam weight .............. WTPXRP43 907-914 Replicate 44 final exam weight .............. WTPXRP44 915-922 Replicate 45 final exam weight .............. WTPXRP45 923-930 Replicate 46 final exam weight .............. WTPXRP46 931-938 Replicate 47 final exam weight .............. WTPXRP47 939-946 Replicate 48 final exam weight .............. WTPXRP48 947-954 Replicate 49 final exam weight .............. WTPXRP49 955-962 Replicate 50 final exam weight .............. WTPXRP50 963-970 Replicate 51 final exam weight .............. WTPXRP51 971-978 Replicate 52 final exam weight .............. WTPXRP52 979-986 Certificate availability status ............. NTCERT 987 Record type ................................. NTRECTYP 988 Resident status recode ...................... NTRSTATR 989 Record weight ............................... NTRECWT 990 Place or facility of birth .................. NTPLDEL 991-992 Attendant at birth .......................... NTBIRATT 993 Metropolitan - nonmetropolitan recode ....... NTMETROR 994 Reported age of mother used flag ............ NTMAGEFL 995 Age of mother imputation flag ............... NTMAGEIM 996 Age of mother recode ........................ NTMAGER 997-998 Hispanic origin of mother recode ............ NTMETHNR 999 Race of mother imputation flag .............. NTMRACIM 1000 Race of mother .............................. NTMRACE 1001 Education of mother recode .................. NTMEDUCR 1002-1003 Marital status of mother imputation flg ..... NTMSTIMP 1004 Marital Status of mother .................... NTMMRST 1005 Place of birth of mother recode ............. NTMPOBR 1006 Adequacy of care recode (Kessner index) ..... NTADEQUA 1007 Number of previous live births-living ....... NTNLBNLR 1008-1009 Number of previous live births-dead ......... NTNLBNDR 1010 Interval since last live birth recode ....... NTISLLBR 1011-1013 Number of other terminations recode ......... NTTERMR 1014 Interv. months since last other term. ....... NTISLTR 1015-1017 Interv. between deliveries recode ........... NTINDLVR 1018-1020 Outcome of last pregnancy ................... NTOUTCOM 1021 Interpregnancy interval - in months ......... NTINTPGR 1022-1024 Live birth order recode ..................... NTLBOR 1025-1026 Total birth order recode .................... NTTBOR 1027-1028 Month pregnancy prenatal care began ......... NTMONPRE 1029-1030 Number of prenatal visits recode ............ NTTNPVR 1031-1032 Reported age of father used flag ............ NTFAGEFL 1033 Age of father recode ........................ NTFAGER 1034-1036 Hispanic origin of father recode ............ NTFETHNR 1037 Race of father .............................. NTFRACE 1038 Education of father recode .................. NTFEDUCR 1039-1040 Clinical estimate of gestation used ......... NTGESTFL 1041 Gestation imputation flag ................... NTGESTIM 1042 Period of gestation recode .................. NTGESTR 1043-1045 Sex imputation flag ......................... NTSEXIMP 1046 Sex ......................................... NTSEX 1047 Race of child ............................... NTCRACE 1048 Birth weight recode - in grams .............. NTBWTR 1049-1052 Plurality imputation flag ................... NTPLUIMP 1053 Plurality recode ............................ NTPLURR 1054 One minute Apgar score recode ............... NTOMAPSR 1055-1056 Five minute Apgar score recode .............. NTFMAPSR 1057-1058 Clinical estimate of gestation recode ....... NTCGESTR 1059-1060 Vaginal ..................................... NTVAGINA 1061 Vaginal birth after previous C-section ...... NTVBAC 1062 Primary C-section ........................... NTPRIMAC 1063 Repeat C-section ............................ NTREPEAC 1064 Vaginal or C-section recode ................. NTDELIVR 1065 Forceps ..................................... NTFORCEP 1066 Vacuum ...................................... NTVACUUM 1067 Anemia recode ............................... NTAORHR 1068 Cardiac disease ............................. NTCARDIA 1069 Acute or chronic lung disease ............... NTLUNG 1070 Diabetes .................................... NTDIABET 1071 Genital herpes .............................. NTHERPES 1072 Hydramnios/Olighydramnios ................... NTHYDRA 1073 Hypertension, chronic ....................... NTCHYPER 1074 Hypertension, pregnancy-associated .......... NTPHYPER 1075 Eclampsia ................................... NTECLAMP 1076 Incompetent cervix .......................... NTINCERV 1077 Previous infant 4000+ grams ................. NTPR4000 1078 Previous preterm or small-for-gestation ..... NTPRTERM 1079 Renal disease ............................... NTRENAL 1080 Rh sensitization ............................ NTRH 1081 Uterine bleeding ............................ NTUTERIN 1082 Other medical risk factors .................. NTOTHRMR 1083 Tobacco use during pregnancy recode ......... NTTOBACR 1084 Avg. number of cigarettes per day rec. ...... NTCIGARR 1085-1086 Alcohol use during pregnancy recode ......... NTALCOHR 1087 Average number of drinks per week recode .... NTDRINKR 1088 Weight gain recode .......................... NTWTGNR 1089-1090 Amniocentesis ............................... NTAMNIO 1091 Electronic fetal monitoring ................. NTMONITO 1092 Induction of labor .......................... NTINDUCT 1093 Stimulation of labor ........................ NTSTIMUL 1094 Tocolysis ................................... NTTOCOL 1095 Ultrasound .................................. NTULTRAS 1096 Other obstetric procedures .................. NTOTHROB 1097 Febrile ..................................... NTFEBRIL 1098 Meconium, moderate/heavy .................... NTMECONI 1099 Premature rupture of membrane ............... NTRUPTUR 1100 Abruptio placenta ........................... NTABRUPT 1101 Placenta previa ............................. NTREPLAC 1102 Other excessive bleeding .................... NTEXCBLD 1103 Seizures during labor ....................... NTSEIZUR 1104 Precipitous labor (<3 hours) ................ NTPRECIP 1105 Prolonged labor (>20 hours) ................. NTPRLONG 1106 Dysfunctional labor ......................... NTDYSFUN 1107 Breech/malpresentation ...................... NTBREECH 1108 Cephalopelvic disproportion ................. NTCEPHAL 1109 Cord prolapse ............................... NTCORD 1110 Anesthetic complications .................... NTANESTH 1111 Fetal distress .............................. NTDISTRE 1112 Other complications of labor ................ NTOTHRLB 1113 Anemia (Hct.<39/Hgb.<13) .................... NTNANEMI 1114 Birth injury ................................ NTINJURY 1115 Fetal alcohol syndrome ...................... NTALCOSY 1116 Hyaline membrane disease .................... NTHYALIN 1117 Meconium aspiration syndrome ................ NTMECONS 1118 Assisted ventilation, < 30 minutes .......... NTVENL30 1119 Assisted 30+ minutes ........................ NTVEN30M 1120 Other abnormal conditions recode ............ NTOTHABR 1121 Other circulatory/respiratory anomalies ..... NTCIRCUL 1122 Club foot ................................... NTCLUBFT 1123 Othr musculoskeletal/integumental anom. ..... NTMUSCUL 1124 Major congenital anomalies recode ........... NTCONMJR 1125 Minor congenital anomalies recode ........... NTCONMNR 1126 Marital status (by state) ................... NTFLMSST 1127 Education of parents (by state) ............. NTFLEPST 1128 Education of mother ......................... NTFLEDM 1129 Education of father ......................... NTFLEDF 1130 Date of last menses (by state) .............. NTFLNMST 1131 Date of last live birth (by state) .......... NTFLLBST 1132 Date of last other termination by state ..... NTFLLTST 1133 Number of prenatal visits (by state) ........ NTFLPVST 1134 One minute Apgar score (by state) ........... NTFL1APS 1135 Five minute Apgar score (by state) .......... NTFL5APS 1136 Clinical estimate of gestation .............. NTFLGEST 1137 Tobacco use ................................. NTFLTOBU 1138 Alcohol use ................................. NTFLALCU 1139 Weight gain ................................. NTFLWTGN 1140 Congential anomalies ........................ NTFLCONG 1141 GENERAL NOTES Many variables on this data file were recoded to protect confidentiality. The minimum or maximum categories were collapsed in order to prevent potential identification of individuals. A few variables from the birth certificates, age of mother or father, race, Hispanic origin, marital status of mother, gestation period, and plurality were imputed. Variables beginning with the letters NTFL... are reporting flags which indicate whether or not the specified item is included on the birth certificates of the state of residence OR that the SMSA of residence is composed entirely of state(s) which report the specified item. Variables that contain a blank or missing value on a record indicate that the variable did not appear on that state's birth certificates. Variables that contain a code of 8, 88, 888, etc. where the documentation says the code stands for "blank but applicable" indicate that the item to be completed did appear on the state's standard birth certificate but there was no codable value on the birth record for this particular child. Analysts should use caution when using NTOUTCOM (outcome of previous delivery), interval since last delivery (NTINDLVR), interval since last pregnancy (NTINTPGR), and interval since last other termination (NTISLTR). These variables were not computed if the month or year of last other termination was blank even when it is clear that the mother never had any fetal deaths, miscarriages, or abortions. For example, the total birth order may be stated as 2, the number of previous live births may be stated as 1, and the month and year of last live birth may be given. It seems obvious that the mother had no other terminations, but if the date of last other termination was blank on the birth certificate file, the NTOUTCOM variable was not computed (it is blank) and the other intervals that involve the date of last other termination (NTINDLVR, NTINTPGR, and NTISLTR) are blank. DMPFSEQ: Family sequence number This variable can be used to determine all family members who participated in the survey. Sample persons who have identical family sequence numbers (i.e., match on all 5 digits) are members of the same family. DMPSTAT: Examination/interview status This variable identifies the interview or examination status of all persons selected for the NHANES III sample. Interviewed persons completed preselected questions in specific sections of the Household Adult or Youth Questionnaires. Mobile examination center (MEC) examined persons were interviewed and successfully completed at least one examination component in the MEC. Home-examined persons were interviewed and successfully completed at least one home examination component. The home examination was an option for frail older adults, infants 2-11 months of age, and other adults who were unable to come to the MEC. DMARETHN: Race-ethnicity This variable, based on the NHANES III survey design, was derived from many sources of data and is based on reported race and ethnicity. The "Other" category includes all Hispanics, regardless of race, who were not Mexican-American and also includes all non-Hispanics from racial groups other than white or black. DMARACER: Race This variable was obtained from two primary sources: the Screener and the Family Questionnaire. Prior to the selection of the sample, race (Black, White, Other) was self-reported or reported by proxy in the Screener Questionnaire. During the administration of the Family Questionnaire, race was self-reported or reported by the respondent of the Family Questionnaire from five categories (Aleut, Eskimo, American Indian; Asian or Pacific Islander; Black; White; Other). Responses from the two sources were adjudicated, as necessary, to create a three level variable (Black, White, Other). DMAETHNR: Ethnicity This variable was obtained from two primary sources: the Screener and the Family Questionnaire. As part of both interviews, hand cards were used to determine Mexican/Mexican-American or Other Latin American/ Spanish ancestry or national origin. Responses of non-Hispanic ancestry or national origin were categorized as "Other." Responses from the two interviews were adjudicated, as necessary, and this three level variable was created. HSAGEIR: Age at interview (Screener) Age is calculated using the birth date which is obtained from the Screener Questionnaire. The variable HSAGEU provides the age unit (months or years) for HSAGEIR. HSAITMOR: Age at interview in months (Screener) Age of the sample child in months is calculated by computing number of months between the Screener Questionnaire date and the child's date of birth. This variable is created for analyses where exact age at the interview is needed. HSAITMOR differs slightly from the age in years (HSAGEIR), the variable most often used for analyses. HSFSIZER: Family Size Family size represents the total number of related persons living in a household (single dwelling unit). All household members are rostered by family during the Screener interview. Household members related to the family reference person (knowledgeable household member 17 years or older who owned or rented the dwelling unit) by blood or marriage are considered part of the family. Adopted children, foster- and god-children are also included, if they were living in the dwelling unit. However, family members who are away at college or living independently are not included. Other household members who were unrelated to the reference person are considered members of separate families. See note for Household Size (HSHSIZER). HSHSIZER: Household Size Household size represents the total number of persons living in a single dwelling unit, both related and unrelated. All permanent household members are rostered according to their family as part the Screener interview. This is done in order to obtain a complete list of all persons living or staying in the dwelling unit, and to distinguish household and family members. See note for Family Size (HFHSIZER). DMPMETRO: Urbanization classification based on USDA Rural-Urban continuum codes These classifications are based on the USDA Rural-Urban codes (Butler and Beale, 1993) that describe metropolitan and non-metropolitan counties by degree of urbanization and nearness to metropolitan areas. The USDA codes are recoded into two categories to prevent identification of counties that were sampled in the survey. DMPCREGN: Census region The United States was divided into four broad geographic regions as defined by the Bureau of Census. Because all states were not included in the selected sample, regional estimates may not be representative for a given region. DMPPIR: Poverty income ratio (or poverty index) The poverty income ratio (PIR) is computed as a ratio of two components. The numerator is the midpoint of the observed family income category in the Family Questionnaire variable: HFF19R. The denominator is the poverty threshold based on the family composition, the age of family reference person, and the calendar year in which the family was interviewed. Poverty threshold values (in dollars) are produced annually by the Census Bureau (Series P-60). These threshold values are based on calendar years and adjusted for changes caused by inflation between calendar years. Reports for each of the calendar years in the survey (1988-94) were used in the calculation of PIR. For the years 1991 and 1994, data from preliminary reports were used. The poverty income ratio allows income data to be analyzed in a comparable manner across the six years of the survey and with previous NHANES. Persons who reported having had no income are assigned a zero value for PIR. A substantial proportion of persons refused to report their income or income category during the Family Questionnaire. Due to the income nonresponse the potential for bias in PIR may be high. Users are cautioned to examine potential nonresponse bias for PIR and other income variables. Survey Design Data SDPPHASE: Phase of NHANES III survey For operational purposes, 81 primary sampling units are divided into 89 survey locations (or stands) and randomly allocated to two three-year phases. Phase 1 data were collected from October 1988 through October 1991 and Phase 2 data were collected from October 1991 through October 1994. SDPPSU6, SDPPSU1, SDPPSU2 and SDPSTRA6, SDPSTRA1, SDPSTRA2: Pseudo PSU pair codes and pseudo strata codes Because NHANES III is based upon a complex sample design, the assumptions of many statistical tests and routinely available statistical programs are not met. For this reason, when estimates of the variances of statistics are computed, the technique of estimation must be based upon complex sampling theory. In order to provide users with the capability of estimating the complex sample variances, 49 pseudo strata and a pair of Primary Sampling Unit (PSU) codes per stratum were designed. A software package, "SUDAAN- Software for the Statistical Analysis of Correlated Data" (Shah, 1995), was developed by the Research Triangle Institute to analyze complex sample design data like NHANES. SUDAAN uses strata and PSU codes to conduct analysis with two PSU per stratum design. Therefore, definitions of pseudo strata and PSU provided in this data file should be used to compute complex sample variances in analyses. Other software available for estimation of complex sample variance may also be used. For further discussion of methods of variance estimation in NHANES III, see additional information on this subject in Weighting and Estimation Methodology (U.S. DHHS, 1996) and NHANES III Analytic and Reporting Guidelines (U.S. DHHS, 1996). Sampling Weights WTPFQX6, WTPFQX1, WTPFQX2: Total NHANES III and phase-specific final interview weights These sampling weights are used only for items collected during the household interviews. To compute final interview weights, final basic weights were first adjusted for nonresponse to household interview, then post-stratified to the unpublished Current Population Survey 1990 (Phase 1) and 1993 (Phase 2) population control estimates of the U.S. population adjusted for undercount. For details, see Weighting and Estimation Methodology (U.S. DHHS, 1996) and NHANES III Analytic and Reporting Guidelines (U.S. DHHS, 1996). WTPFEX6, WTPFEX1, WTPFEX2: Total NHANES III and phase-specific final MEC examination weights These MEC sampling weights are used for analysis of measurements or interview items collected in the MEC. Persons who were not examined in the MEC have a sampling weight of zero and should be excluded from analyses. To compute final MEC examination weights, final interview weights were first adjusted for nonresponse to MEC examinations, then post-stratified to the unpublished Current Population Survey 1990 (Phase 1) and 1993 (Phase 2) population control estimates of the U.S. population adjusted for undercount. For details, see Weighting and Estimation Methodology (U.S. DHHS, 1996) and NHANES III Analytic and Reporting Guidelines (U.S. DHHS, 1996). WTPFHX6, WTPFHX1, WTPFHX2: Total NHANES III and phase-specific MEC+home examination weights These MEC+home sampling weights are used for analysis of the examination items where measurements or interview items were collected in the MEC and home. Persons who were not examined in the MEC or home have a sampling weight of zero and should be excluded from analyses. To compute final MEC+home examination weights, final interview weights were first adjusted for non-response to MEC and home examinations, then post-stratified to unpublished Current Population Survey 1990 (Phase 1) and 1993 (Phase 2) population control estimates of the U.S. population adjusted for undercount. No separate sampling weights were computed for home examinees. For details, see Weighting and Estimation Methodology (U.S. DHHS, 1996) and NHANES III Analytic and Reporting Guidelines (U.S. DHHS, 1996). WTPFALG6, WTPFALG1, WTPFALG2: Total NHANES III and phase-specific allergy examination subsample weights These subsample weights are for analysis of allergy measurements. Allergy skin reactivity tests were administered to all MEC-examined persons aged 6-19 years and a random half-sample of the adults aged 20-59 years. Eligible MEC-examined persons who did not complete the allergy tests have a sampling weight of zero and should be excluded from the analyses. Final MEC examination weights were first adjusted for selection of the half-sample among adults (20-59 years), and post-stratified to the unpublished Current Population Survey 1990 (Phase 1) and 1993 (Phase 2) population control estimates of the U.S. population adjusted for undercount in the final step. For details, see Weighting and Estimation Methodology (U.S. DHHS, 1996) and NHANES III Analytic and Reporting Guidelines (U.S. DHHS, 1996). WTPQRP1--WTPQRP52: Fay's BRR Replicate interview sample weights To allow for alternative methods to estimate variance, 52 replicate weights were computed using repeated sampling method where WESVAR or other software that use repeated samples can be used for estimating variance. Fay's method (see Fay, 1990; Judkins, 1990) was used to draw half samples and adjust sampling weights in each of the random half samples. Sampling weights in one half sample were multiplied by the factor k=1.7 and in the other half sample by k=0.3 using the Fay's method. After this adjustment, sampling weights were further adjusted for non-response and post-stratified using the same procedure as the final full sample interview weights. These weights should be used only for estimating variance of items from the household adult and youth interviews. For details, see Weighting and Estimation Methodology (U.S. DHHS, 1996) and NHANES III Analytic and Reporting Guidelines (U.S. DHHS, 1996). WTPXRP1--WTPXRP52: Fay's BRR Replicate weights for MEC-examined sample To allow for alternative methods to estimate variance, 52 replicate weights were computed using repeated sampling method where WESVAR or other BRR type software can be used to estimate variance. Fay's method (see Fay, 1990; Judkins, 1990) was used to draw half samples and adjust sampling weights in each of the random half samples. Sampling weights in one half sample were multiplied by the factor k=1.7 and in the other half sample by k=0.3 using Fay's method. After this adjustment, weights were further adjusted for nonresponse and were post-stratified using the same procedure as the full sample final weights. These weights should be used only for estimating variance of outcome measurements or interview items from the MEC Examination. For details, see additional information on this subject in Weighting and Estimation Methodology U.S. DHHS, 1996) and NHANES III Analytic and Reporting Guidelines (U.S. DHHS, 1996). Data Based on Birth Certificates FOR IMPORTANT ADDITIONAL INFORMATION AND DEFINITIONS REGARDING THE BIRTH CERTIFICATE VARIABLES WHICH ALL BEGIN WITH THE LETTERS "NT", PLEASE BE SURE TO READ THE SECTION ENTITLED: CLASSIFICATION IN "Vital Statistics Classification and Coding Instructions for Live Birth Records, 1994," NCHS Instruction Manual, Part 3a. The general rules used to classify geographic and personal items for live births are set forth in "Vital Statistics Classification and Coding Instructions for Live Birth Records, 1994," NCHS Instruction Manual, Part 3a. The classification of certain important items is discussed in the following pages. The rules followed in the classification of geographic areas for live births are contained in the instruction manual mentioned previously. The geographic code structure is in another manual, "Vital Records Geographic Classification, 1982," NCHS Instruction Manual, Part 8. NTCERT: Certificate availability If a matching birth certificate could not be obtained for any reason, this variable was coded 2. Reasons for failure to obtain a matching certificate included inability to obtain parental consent, state unable to locate matching certificate, incorrect last name, missing or incorrect mother's maiden name, adopted children, incorrect birth date, wrong state or county listed on consent form, etc. NTRSTATR: Resident status recode Code 3, "Nonresident: State of occurrence and residence are different or mother is foreign," includes three cases where the mother resides outside of the United States, according to the birth certificate. NTPLDEL and NTBIRATT: Place or facility of birth and attendant The 1989 revision of the U.S. Standard Certificate of Live Birth includes separate categories for freestanding birthing centers, the mother's residence, and clinic or doctor's office as the place of birth. In previous years, place of birth was classified simply as either "In hospital" or "Not in hospital." Births occurring in hospitals, institutions, clinics, centers, or homes were included in the category "In hospital." In this context the word "homes" does not refer to the mother's residence but to an institution, such as a home for unmarried women. Birthing centers were included in either category, depending on each State's assessment of the facility. Beginning in 1989, births occurring in clinics and in birthing centers not attached to a hospital are classified as "Not in hospital." The "Not in hospital" category includes births for which no information is reported on place of birth. Babies born on the way to or on arrival at the hospital are classified as having been born in the hospital. This may account for some of the hospital births not delivered by physicians or midwives. NTMETROR: Metropolitan-nonmetropolitan county of residence recode Metropolitan statistical areas are those established by the U.S. Office of Management and Budget as of April 1, 1990, and used by the U.S. Bureau of the Census (U.S. Bureau of the Census, 1991) except in the New England States. Except in the New England States, an MSA has either a city with a population of at least 50,000, or a Bureau of the Census urbanized area of at least 50,000 and a total MSA population of at least 100,000. In the New England States, the U.S. Office of Management and Budget uses towns and cities rather than counties as geographic components of MSAs. NCHS cannot, however, use this classification for these States because its data are not coded to identify all towns. Instead, the New England County Metropolitan Areas (NECMAs) are used. These areas are established by the U.S. Office of Management and Budget (U.S. Office of Management and Budget, 1975) and are made up of county units. Independent cities and counties included in MSAs or NECMAs are included in data for metropolitan counties; all other counties are classified as nonmetropolitan. Code 2, "Nonmetropolitan county or foreign", includes three cases where the mother resides outside of the United States, according to the birth certificate. NTMAGEFL: Reported age of mother used flag This variable indicates whether the mother's age is derived from the mother's date of birth or from her age in years. Beginning in 1989 an item on the birth certificate asks for "Date of Birth." In previous years, "Age (at time of this birth)" was requested. Not all States have revised this item, and therefore the age of mother either is derived from the reported month and year of birth or coded as stated on the certificate. The age of mother is edited for upper and lower limits. When the age of mother is computed to be under 10 years or 50 years or over, it is considered not stated and is assigned as described below. NTMAGEIM: Age of mother imputation flag Not stated date of birth of mother -- Beginning in 1964 birth records with date of birth of mother and/or age of mother not stated have had age imputed according to the age of mother from the previous birth record of the same race and total-birth order (total of fetal deaths and live births). (See "Vital Statistics Computer Edits for Natality Data," NCHS Instruction Manual, Part 12, page 9.) NTMEDUCR: Education of mother recode The educational attainment of either parent is defined as "the number of years of school completed." Only those years completed in "regular" schools are counted, that is, a formal educational system of public schools or the equivalent in accredited private or parochial schools. Business or trade schools, such as beauty and barber schools, are not considered "regular" schools for the purposes of this item. No attempt has been made to convert years of school completed in foreign school systems, ungraded school systems, and so forth, to equivalent grades in the American school system. Such entries are included in the category "Not stated." Persons who have completed only a partial year in high school or college are tabulated as having completed the highest preceding grade. For those certificates on which a specific degree is stated, years of school completed is coded to the level at which the degree is most commonly attained; for example, persons reporting B.A., A.B., or B.S. degrees are considered to have completed 16 years of school. Education not stated -- The category "Not stated" includes all records in reporting areas for which there is no information on years of school completed as well as all records for which the information provided is not compatible with coding specifications. NTMMRST: Marital status Beginning in 1980, a birth in a nonreporting State is classified as occurring to a married woman if the parents' surnames are the same, or if the child's and father's surnames are the same and the mother's current surname cannot be obtained from the informant item of the birth certificate. A birth is classified as occurring to an unmarried woman if the father's name is missing, if the parents' surnames are different, or if the father's and child's surnames are different and the mother's current surname is missing. When births to unmarried women are reported as second or higher-order births, it is not known whether the mother was married or unmarried when the previous deliveries occurred, because her marital status at the time of these earlier births is not available from the birth record. NTADEQUA: Adequacy of care recode (Kessner index) This recode is based on a modified Kessner criterion. Month Prenatal Care Began, Number of Prenatal Visits, and Gestation are the items used to generate this recode. NTISLLBR: Interval since last live birth recode The interval since the last live birth is the difference in months between the date of last live birth and the date of present birth. For an interval to be computed, both the month and year of the last live birth must be valid. This interval is computed only for events to mothers who have had at least one previous live birth. Zero interval - An interval of zero months since the last live birth indicates the second born of a set of twins, the second or third born of a set of triplets, and so forth. NTISLTR: Interval since last other termination recode This number is the difference in months between the date of the last "other termination" (non-live birth prior to the NHANES III sample child) and the date of the NHANES III child's birth. The interval is computed only if month and year of last other termination are valid. The interval is computed only if the mother has had a previous pregnancy that terminated in a non-live birth. NTINDLVR: Interval between deliveries recode This variable is the number of months between the delivery just prior to that of the sample child and the date of birth of the sample child. It is calculated by subtracting the date of the previous delivery (prior to the NHANES III sample child) from the date of the NHANES III child's birth. An interval of zero indicates that the sample child is the second or higher order child of a multiple pregnancy. The interval is computed only if both the month and year of the previous delivery are valid. The date of previous delivery depends on the presence of both a valid date of last live birth and a valid date of last other termination. The interval is calculated only for cases where the mother had a delivery prior to that of the sample child. NTOUTCOM: Outcome of last delivery This variable refers to the delivery immediately prior to the birth of the sample child. NTOUTCOM was calculated only if both month and year of last live birth and last other termination were valid. If the sample child is the second or higher order born of a multiple pregnancy, NTOUTCOM, if present, reflects the outcome of the delivery just prior to the sample child, i.e., the older twin, triplet, etc. NTINTPGR: Interval since last pregnancy recode This variable represents the interval in months between the end of the last pregnancy and the beginning of the pregnancy with the sample child. The variable was computed using the date of last menstrual period (LMP), the date of last live birth, and the date of last other termination. NTINTPGR was not calculated if the month or year of LMP, of last live birth and last other termination are not all valid. Since the date of LMP is prior to the date of last live birth or other termination in a multiple delivery where the sample child is not the first born of the multiples, NTINTPGR is 0. NTLBOR: Live birth order recode Live-birth order indicates what number the NHANES III sample child represents; for example, a baby born to a mother who has had two previous live births (even if one or both are not now living) has a live-birth order of three. Live-birth order is determined from two items on the birth certificate, "Live births now living" and "Live births now dead." NTMONPRE: Month of pregnancy prenatal care began For those records in which the name of the month is entered for this item instead of first, second, third, and so forth, the month of pregnancy in which prenatal care began is determined from the month named and the month last normal menses began. For these births, if the item "Date last normal menses began" is not stated, the month of pregnancy in which prenatal care began is tabulated as not stated. NTFAGEFL: Reported age of father used flag A code of 1 indicates that the father's age as reported in years on the certificate was used rather than the father's date of birth, which was not on the certificate. NTFAGER: Age of father recode Age of father is derived from the reported date of birth or coded as stated on the birth certificate. If the age is under 10 years, it is considered not stated and grouped with those cases for which age is not stated on the certificate. NTFEDUCR: Education of father recode The educational attainment of either parent is defined as "the number of years of school completed." Only those years completed in "regular" schools are counted, that is, a formal educational system of public schools or the equivalent in accredited private or parochial schools. Business or trade schools, such as beauty and barber schools, are not considered "regular" schools for the purposes of this item. No attempt has been made to convert years of school completed in foreign school systems, ungraded school systems, and so forth, to equivalent grades in the American school system. Such entries are included in the category "Not stated." Persons who have completed only a partial year in high school or college are tabulated as having completed the highest preceding grade. For those certificates on which a specific degree is stated, years of school completed is coded to the level at which the degree is most commonly attained; for example, persons reporting B.A., A.B., or B.S. degrees are considered to have completed 16 years of school. Education not stated--The category "Not stated" includes all records in reporting areas for which there is no information on years of school completed as well as all records for which the information provided is not compatible with coding specifications. NTGESTFL: Clinical estimate of gestation used flag; and NTGESTR: Period of gestation recode The period of gestation is defined as beginning with the first day of the last normal menstrual period (LMP) and ending with the day of the birth. The LMP is used as the initial date because it can be more accurately determined than the date of conception, which usually occurs 2 weeks after the LMP. Births occurring before 37 completed weeks of gestation are considered to be "preterm" or "premature" for purposes of classification. At 37-41 weeks gestation, births are considered to be "term," and at 42 completed weeks and over, "postterm." These distinctions are according to the ICD-9 definitions. The 1989 revision of the U.S. Standard Certificate of Live Birth includes a new item, "clinical estimate of gestation," that is being compared with length of gestation computed from the LMP date when the latter appears to be inconsistent with birth weight. This is done for normal-weight births of apparently short gestations and very low-birth weight births reported to be full term. The clinical estimate also was used if the date of the LMP was not reported. In cases where the reported birth weight was inconsistent with both the LMP-computed gestation and the clinical estimate of gestation, the LMP-computed gestation was used and birth weight was reclassified as "not stated." These changes result in only a very small discontinuity in the data. For further information on the use of the clinical estimate of gestation see "Computer Edits for Natality Data, Effective 1989," NCHS Instruction Manual, Part 12, pages 34-36. Beginning in 1981, weeks of gestation have been imputed for records with missing day of LMP when there is a valid month and year. Each such record is assigned the gestational period in weeks of the preceding record that has a complete LMP date with the same computed months of gestation and the same 500-gram birth weight interval. The effect of the imputation procedure is to increase slightly the proportion of preterm births and to lower the proportion of births at 39, 40, 41, and 42 weeks of gestation. A more complete discussion of this procedure and its implications is presented in a previous report (Taffel S, Johnson D, Heuser R, 1982). Because of postconception bleeding or menstrual irregularities, the presumed date of LMP may be in error. In these instances the computed gestational period may be longer or shorter than the true gestational period, but the extent of such errors is unknown. NTSEX and NTCRACE: Sex of child and Race of child These items may differ from the values recorded in NHANES III for this child. The NTSEX and NTCRACE variables came from the birth certificate. NTPLURR: Plurality recode Plurality refers to a multiple pregnancy, i.e., twins, triplets, etc. If the child on the certificate was part of a multiple pregnancy, this variable will reflect that status regardless of the birth order within the multiples. Even if the other twin, triplet, etc. was a fetal death, the plurality variable will still reflect the multiple pregnancy. NTOMAPSR and NTFMAPSR: One minute and Five minute Apgar score recodes One- and 5-minute Apgar scores were added to the U.S. Standard Certificate of Live Birth in 1978 to evaluate the condition of the newborn infant at 1 and 5 minutes after birth. The Apgar score is a useful measure of the need for resuscitation and a predictor of the infant's chances of surviving the first year of life. It is a summary measure of the infant's condition based on heart rate, respiratory effort, muscle tone, reflex irritability, and color. Each of these factors is given a score of 0, 1, or 2; the sum of these 5 values is the Apgar score, which ranges from 0 to 10. A score of 10 is optimal, and a low score raises some doubts about the survival and subsequent health of the infant. NTVAGINA, NTVBAC, NTPRIMAC, NTREPEAC, NTDELIVR, NTFORCEP, NTVACUUM: Methods of delivery - Vaginal, Vaginal birth after previous C-section, Primary C-section, Repeat C-section, Vaginal or C-section recode, Forceps, and Vacuum. The birth certificate contains a check box item on method of delivery. The choices include vaginal delivery, with the additional options of forceps, vacuum, and vaginal birth after previous cesarean section (VBAC), as well as a choice of primary or repeat cesarean. When only forceps, vacuum, or VBAC is checked, a vaginal birth is assumed. NTAORHR, NTCARDIA, NTLUNG, NTDIABET, NTHERPES, NTHYDRA, NTCHYPER, NTPHYPER, NTECLAMP, NTINCERV, NTPR4000, NTPRTERM, NTRENAL, NTRH, NTUTERIN, NTOTHRMR: Medical risk factors for this pregnancy - Anemia or hemoglobinopathy recode (also see separate note below for NTAORHR), Cardiac disease, Acute or chronic lung disease, Diabetes, Genital herpes, Hydramnios/Olighydramnios, Chronic hypertension, Pregnancy-associated hypertension, Eclampsia, Incompetent cervix, Previous infant 4000+ grams, Previous infant preterm or small for gestational age, Renal disease, RH sensitization, Uterine bleeding, or Other medical risk factors The birth certificate format allows for the designation of more than one risk factor and includes a choice of "None." Accordingly, if the item is not completed, it is classified as "Not stated." The following definitions are adapted and abbreviated from a set of definitions compiled by a committee of Federal and State health statistics officials for the Association for Vital Records and Health Statistics (Brockert JE, Stockbauer JW, Senner JW, et al, 1990). Anemia--Hemoglobin level of less than 10.0 g/dL during pregnancy or a hematocrit of less than 30 percent during pregnancy. Cardiac disease--Disease of the heart. Acute or chronic lung disease--Disease of the lungs during pregnancy. Diabetes--Metabolic disorder characterized by excessive discharge of urine and persistent thirst; includes juvenile onset, adult onset, and gestational diabetes during pregnancy. Genital herpes--Infection of the skin of the genital area by herpes simplex virus. Hydramnios/Oligohydramnios--Any noticeable excess (hydramnios) or lack (oligohydramnios) of amniotic fluid. Hemoglobinopathy--A blood disorder caused by alteration in the genetically determined molecular structure of hemoglobin (for example, sickle cell anemia). Hypertension, chronic--Blood pressure persistently greater than 140/90, diagnosed prior to onset of pregnancy or before the 20th week of gestation. Hypertension, pregnancy-associated--An increase in blood pressure of at least 30 mm Hg systolic or 15 mm Hg diastolic on two measurements taken 6 hours apart after the 20th week of gestation. Eclampsia--The occurrence of convulsions and/or coma unrelated to other cerebral conditions in women with signs and symptoms of pre-eclampsia. Incompetent cervix--Characterized by painless dilation of the cervix in the second trimester or early in the third trimester of pregnancy, with prolapse of membranes through the cervix and ballooning of the membranes into the vagina, followed by rupture of membranes and subsequent expulsion of the fetus. Previous infant 4,000+ grams--The birth weight of a previous live-born child was over 4,000 grams (8 lbs 13 oz). Previous preterm or small-for-gestational-age infant--Previous birth of an infant prior to term (before 37 completed weeks of gestation) or of an infant weighing less than the 10th percentile for gestational age using a standard weight-for-age chart. Renal disease--Kidney disease. Rh sensitization--the process or state of becoming sensitized to the Rh factor as when an Rh-negative woman is pregnant with an Rh-positive fetus. Uterine bleeding--Any clinically significant bleeding during the pregnancy, taking into consideration the stage of pregnancy; any second or third trimester bleeding of the uterus prior to the onset of labor. NTAORHR: Anemia or hemoglobinopathy recode The anemia and hemoglobinopathy variables are combined due to small cell sizes in order to prevent potential identification of individuals. NTTOBACR, NTCIGARR, NTALCOHR, NTDRINKR: Tobacco and alcohol use during pregnancy recodes The check box format on the birth certificate allows for classification of a mother as a smoker or drinker during pregnancy and for reporting the average number of cigarettes smoked per day or drinks consumed per week. When smoking and/or drinking status is not reported or is inconsistent with the quantity of cigarettes or drinks reported, the status is changed to be consistent with the amount reported. For example, if the drinking status is reported as "no" but one or more average drinks a week are reported, the mother is classified as a drinker. If the number of cigarettes smoked per day is reported as one or more, the mother is considered a smoker. When one (or a fraction of one) drink a week is recorded, the mother is classified as a drinker. For records on which the number of drinks or number of cigarettes is reported as a span, for example, 10-15, the lower number is used. The number of drinkers and number of drinks reported on birth certificates are believed to underestimate actual alcohol use. NTWTGNR: Weight gain (during pregnancy) recode Weight gain is reported in pounds. A loss of weight is reported as zero gain. NTAMNIO, NTMONITO, NTINDUCT, NTSTIMUL, NTTOCOL, NTULTRAS, NTOTHROB: Obstetric procedures - Amniocentesis, Electronic fetal monitoring, Induction of labor, Stimulation of Labor, Tocolysis, Ultrasound, Other obstetric procedures. This birth certificate item includes six specific obstetric procedures. Birth records with "Obstetric procedures" left blank are considered "not stated." The following definitions are adapted and abbreviated from a set of definitions compiled by a committee of Federal and State health statistics officials for the Association for Vital Records and Health Statistics (Brockert JE, Stockbauer JW, Senner JW, et al, 1990). Amniocentesis--Surgical transabdominal perforation of the uterus to obtain amniotic fluid to be used in the detection of genetic disorders, fetal abnormalities, and fetal lung maturity. Electronic fetal monitoring--Monitoring with external devices applied to the maternal abdomen or with internal devices with an electrode attached to the fetal scalp and a catheter through the cervix into the uterus, to detect and record fetal heart tones and uterine contractions. Induction of labor--The initiation of uterine contractions before the spontaneous onset of labor by medical and/or surgical means for the purpose of delivery. Stimulation of labor--Augmentation of previously established labor by use of oxytocin. Tocolysis--Use of medications to inhibit preterm uterine contractions to extend the length of pregnancy and therefore avoid a preterm birth. Ultrasound--Visualization of the fetus and placenta by means of sound waves. NTFEBRIL, NTMECONI, NTRUPTUR, NTABRUPT, NTREPLAC, NTEXCBLD, NTSEIZUR, NTPRECIP, NTPRLONG, NTDYSFUN, NTBREECH, NTCEPHAL, NTCORD, NTANESTH, NTDISTRE,NTOTHRLB: Complications of labor and/or delivery - Febrile, Meconium- moderate/heavy, Premature rupture of membrane, Abruptio placenta, Placenta previa, Other excessive bleeding, Seizures during labor, Precipitous labor, Prolonged labor, Dysfunctional labor, Breech/malpresentation, Cephalopelvic disproportion, Cord prolapse, Anesthetic complications, Fetal distress, Other complications of labor and/or delivery. The birth certificate check box format allows for the selection of 15 specific complications and for the designation of more than 1 complication where appropriate. A choice of "None" is also included. Accordingly, if the item is not completed, it is classified as "not stated." Not all of the complications were reported by all reporting States. The following definitions are adapted and abbreviated from a set of definitions compiled by a committee of Federal and State health statistics officials for the Association for Vital Records and Health Statistics (Brockert JE, Stockbauer JW, Senner JW, et al, 1990). Febrile--A fever greater than 100 degrees F. or 38 C. occurring during labor and/or delivery. Meconium, moderate/heavy--Meconium consists of undigested debris from swallowed amniotic fluid, various products of secretion, excretion and shedding by the gastrointestinal tract; moderate to heavy amounts of meconium in the amniotic fluid noted during labor and/or delivery. Premature rupture of membranes (more than 12 hours)--Rupture of the membranes at any time during pregnancy and more than 12 hours before the onset of labor. Abruptio placenta--Premature separation of a normally implanted placenta from the uterus. Placenta previa--Implantation of the placenta over or near the internal opening of the cervix. Other excessive bleeding--The loss of a significant amount of blood from conditions other than abruptio placenta or placenta previa. Seizures during labor--Maternal seizures occurring during labor from any cause. Precipitous labor (less than 3 hours)--Extremely rapid labor and delivery lasting less than 3 hours. Prolonged labor (more than 20 hours)--Abnormally slow progress of labor lasting more than 20 hours. Dysfunctional labor--Failure to progress in a normal pattern of labor. Breech/Malpresentation--At birth, the presentation of the fetal buttocks rather than the head, or other malpresentation. Cephalopelvic disproportion--The relationship of the size, presentation and position of the fetal head to the maternal pelvis prevents dilation of the cervix and/or descent of the fetal head. Cord prolapse--Premature expulsion of the umbilical cord in labor before the fetus is delivered. Anesthetic complications--Any complication during labor and/or delivery brought on by an anesthetic agent or agents. Fetal distress--Signs indicating fetal hypoxia (deficiency in amount of oxygen reaching fetal tissues). NTNANEMI, NTINJURY, NTALCOSY, NTHYALIN, NTMECONS, NTVENL30, NTVEN30M, NTOTHABR: Abnormal conditions of the newborn - Anemia, Birth injury, Fetal alcohol syndrome, Hyaline membrane disease, Meconium aspiration syndrome, Assisted ventilation less than 30 minutes, Assisted ventilation 30 minutes or more, Other abnormal conditions of the newborn recode. This certificate item provides information on eight specific abnormal conditions. More than one abnormal condition may be reported for a given birth or "None" may be selected. If the item is not completed it is tabulated as "not stated." The following definitions are adapted and abbreviated from a set of definitions compiled by a committee of Federal and State health statistics officials for the Association for Vital Records and Health Statistics (Brockert JE, Stockbauer JW, Senner JW, et al, 1990). Anemia--Hemoglobin level of less than 13.0 g/dL or a hematocrit of less than 39 percent. Birth injury--Impairment of the infant's body function or structure due to adverse influences that occurred at birth. Fetal alcohol syndrome--A syndrome of altered prenatal growth and development occurring in infants born of women who consumed excessive amounts of alcohol during pregnancy. Hyaline membrane disease/RDS--A disorder primarily of prematurity, manifested clinically by respiratory distress and pathologically by pulmonary hyaline membranes and incomplete expansion of the lungs at birth. Meconium aspiration syndrome--Aspiration of meconium by the fetus or newborn, affecting the lower respiratory system. Assisted ventilation (less than 30 minutes)--A mechanical method of assisting respiration for newborns with respiratory failure. Assisted ventilation (30 minutes or more)--Newborn placed on assisted ventilation for 30 minutes or longer. Seizures--A seizure of any etiology. NTOTHABR: Other abnormal conditions of the newborn recode This category includes seizures. The two categories were combined because of small cell sizes in order to prevent potential identification of individuals. NTCIRCUL, NTCLUBFT, NTMUSCUL, NTCONMJR, NTCONMNR: Congenital anomalies of child - Other circulatory/respiratory anomalies, Club foot, Other musculoskeletal/integumental anomalies, Major congenital anomalies recode, Minor congenital anomalies recode. The data provided in this certificate item relate to 21 specific anomalies or anomaly groups. It is well documented that congenital anomalies, except for the most visible and most severe, are incompletely reported on birth certificates. The completeness of reporting specific anomalies depends on how easily they are recognized in the short time between birth and birth registration. The format allows for the identification of more than one anomaly including a choice of "None" should no anomalies be evident. The category "not stated" includes birth records for which the item is not completed. The following definitions are adapted and abbreviated from a set of definitions compiled by a committee of Federal and State health statistics officials for the Association for Vital Records and Health Statistics (Brockert JE, Stockbauer JW, Senner JW, et al, 1990). Anencephalus--Absence of the cerebral hemispheres. Spina Bifida/meningocele--Developmental anomaly characterized by defective closure of the bony encasement of the spinal cord, through which the cord and meninges may or may not protrude. Hydrocephalus--Excessive accumulation of cerebrospinal fluid within the ventricles of the brain with consequent enlargement of the cranium. Microcephalus--A significantly small head. Other central nervous system anomalies--Other specified anomalies of the brain, spinal cord, and nervous system. Heart malformations--Congenital anomalies of the heart. Other circulatory/respiratory anomalies--Other specified anomalies of the circulatory and respiratory systems. Rectal atresia/stenosis--Congenital absence, closure, or narrowing of the rectum. Tracheo-esophageal fistula/Esophageal atresia--An abnormal passage between the trachea and the esophagus; esophageal atresia is the congenital absence or closure of the esophagus. Omphalocele/gastroschisis--An omphalocele is a protrusion of variable amounts of abdominal viscera from a midline defect at the base of the umbilicus. In gastroschisis, the abdominal viscera protrude through an abdominal wall defect, usually on the right side of the umbilical cord insertion. Other gastrointestinal anomalies--Other specified congenital anomalies of the gastrointestinal system. Malformed genitalia--Congenital anomalies of the reproductive organs. Renal agenesis--One or both kidneys are completely absent. Other urogenital anomalies--Other specified congenital anomalies of the organs concerned in the production and excretion of urine, together with organs of reproduction. Cleft lip/palate--Cleft lip is a fissure of elongated opening of the lip; cleft palate is a fissure in the roof of the mouth. These are failures of embryonic development. Polydactyly/syndactyly/adactyly--Polydactyly is the presence of more than five digits on either hands and/or feet; syndactyly is having fused or webbed fingers and/or toes; adactyly is the absence of fingers and/or toes. Club foot--Deformities of the foot, which is twisted out of shape or position. Diaphragmatic hernia--Herniation of the abdominal contents through the diaphragm into the thoracic cavity usually resulting in respiratory distress. Other musculoskeletal/integumental anomalies--Other specified congenital anomalies of the muscles, skeleton, or skin. Down's syndrome--The most common chromosomal defect with most cases resulting from an extra chromosome (trisomy 21). Other chromosomal anomalies--All other chromosomal aberrations. NTCONMJR: Major congenital anomalies of newborn recode This variable combines several categories of anomalies because of small cell sizes and the need to prevent possible identification of individuals. Anomalies that may have been combined in this category include: Anencephalus, Spina bifida/meningocele, Hydrocephalus, Microcephalus, Other central nervous system anomalies, Heart malformations, Tracheo-esophageal fistula/Esophageal atresia, Omphalocele/gastroschisis, Other gastrointestinal anomalies, Renal agenesis, Down's syndrome, and Other chromosomal anomalies. NTCONMNR: Minor congenital anomalies of newborn recode This variable combines several categories of anomalies because of small cell sizes and the need to prevent possible identification of individuals. Anomalies that may have been combined in this category include: Rectal atresia/stenosis, Malformed genitalia, Other urogenital anomalies, Cleft lip/palate, Polydactyly/syndactyly/adactyly, Club foot, Diaphragmatic hernia, Other musculoskeletal/integumental anomalies, and Other congenital anomalies. REFERENCES Barclay GW. Techniques of population analysis. New York: John Wiley & Sons, Inc., 216-22. 1958. 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