Component Description
The NHANES program suspended field operations in March 2020 due to the coronavirus disease 2019 (COVID-19) pandemic. As a result, data collection for the NHANES 2019-2020 cycle was not completed and the collected data are not nationally representative. Therefore, data collected from 2019 to March 2020 were combined with data from the NHANES 2017-2018 cycle to form a nationally representative sample of NHANES 2017-March 2020 pre-pandemic data. These data are available to the public. Please refer to the Analytic Notes section for more details on the use of the data.
The reproductive health section (variable name prefix RHQ) contains questions for females only. Questions on reproductive health include menstrual history, pregnancy history, hormone replacement therapy use, and other related reproductive conditions. A question used to calculate estimated time in months at menarche for youth 12-19 was added in 2017-2018.
Eligible Sample
Female participants aged 12 years and older in the NHANES 2017-March 2020 pre-pandemic sample were eligible.
Interview Setting and Mode of Administration
These questions were asked at the mobile examination center (MEC), by trained interviewers, using the Computer-Assisted Personal Interview (CAPI) system as part of the MEC interview. Both proxy interviewers and interpreters were permitted for these questions.
Quality Assurance & Quality Control
The CAPI system is programmed with built-in consistency checks to reduce data entry errors. CAPI also uses online help screens to assist interviewers in defining key terms used in the questionnaire.
Data Processing and Editing
Edits were made to ensure the completeness, consistency, and analytic usefulness of the data.
Analytic Notes
The COVID-19 pandemic required suspension of NHANES 2019-2020 field operations in March 2020 after data were collected in 18 of the 30 survey locations in the 2019-2020 sample. Because the collected data from 18 locations were not nationally representative, these data were combined with data from the previous cycle (2017-2018) to create a 2017-March 2020 pre-pandemic data file. A special weighting process was applied to the 2017-March 2020 pre-pandemic data file. The examination sample weights in the demographic data file should be used to calculate estimates from the combined cycles. These sample weights are not appropriate for independent analyses of the 2019-2020 data and will not yield nationally representative results for either the 2017-2018 data alone or the 2019-March 2020 data alone. Please refer to the NHANES website for additional information for the NHANES 2017-March 2020 pre-pandemic data, and for the previous 2017-2018 public use data file with specific weights for that 2-year cycle.
This data file contains reproductive health related variables for females 12 years and older. However, only variables contained in both cycles 2017-2018 and 2019-March 2020 are included. Questions unique to either 2017-2018, or 2019-March 2020 can be requested through the NCHS Research Data Center, as well. The public use data file excludes select variables related to pregnancy and hysterectomy for those aged 12-19 years and over 44 years, due to disclosure risks.
Since 1999-2000, questions about reproductive health, target ages, and skip patterns have changed periodically. It is recommended that analysts review questions, documentation, and codebooks, as well as unweighted counts, prior to analysis. In addition, survey design changes have occurred over the cycles. In 2007, pregnant women and persons 12-19 years were no longer oversampled. Additionally, for each of the race/ethnicity domains, the former age domains 12-15 and 16-19 were combined and the age minority domain 40-59 was split into two 10-year age sampling domains: 40-49 and 50-59 years. These changes resulted in an increase in the actual number of participants aged 40-59 years and a decrease in participants aged 12-19 years, as compared to previous cycles. Therefore, unweighted frequencies of certain reproductive conditions may differ slightly in this survey cycle compared to survey cycles prior to 2007.
RHD018: estimated age in months at time of menarche was calculated from date of birth (month and year) and reported age and month at first menarche. For those who reported month of menarche in their birth month, it was not possible to discern which year of age menarche occurred. Therefore, these records were coded as “missing” responses.
RHD143: Current pregnancy status from question: “are you pregnant now?” Note that the response found here may be differ from that found in the pregnancy status variable, RIDEXPRG, in the NHANES DEMO data file.
Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues.