Table of Contents

Component Description

A urine test was performed on survey participants 8 years and older. If the urine pregnancy test was positive on any female participants aged 8-17 years, the result was confirmed using a serum test. All positive test results excluded pregnant women from the DXA and cardiovascular fitness components of the mobile examination center.

Eligible Sample

A pregnancy test was completed on female participants aged 12–59 years and menstruating females aged 8–11 years. However, due to disclosure risks only females between 20 and 44 have urine pregnancy results in this file.

Description of Laboratory Methodology

Urine and serum specimens were tested in the NHANES mobile examination centers. Detailed specimen collection and processing instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM).

The Icon 25 hCG test kit (Beckman Coulter) is a rapid chromatographic immunoassay for the qualitative detection of human chorionic gonadotropin (hCG) in urine or serum to aid in the early detection of pregnancy. The test utilizes a combination of monoclonal and polyclonal antibodies to selectively detect elevated levels of hCG in urine or serum.

A detailed description of the laboratory method used can be found on the NHANES website.

Data Processing and Editing

Instructions on data processing and editing can be found on the NHANES website.

Laboratory Quality Assurance and Monitoring

The NHANES quality control and quality assurance protocols (QA/QC) meet the 1988 Clinical Laboratory Improvement Act mandates. Detailed QA/QC instructions are discussed in the  NHANES Laboratory/Medical Technologists Procedures Manual (LPM).

A detailed description of the quality assurance and quality control procedures can be found on the NHANES website.

Analytic Notes

Refer to the 2011-2012 Laboratory Data Overview for general information on NHANES laboratory data.

The analysis of NHANES 2011-2012 laboratory data must be conducted using the appropriate survey design and demographic variables. The NHANES 2011-2012 Demographics File contains demographic data, health indicators, and other related information collected during household interviews as well as the sample weight variables. The demographics file may be linked to the laboratory data file using the unique survey participant identifier (i.e., SEQN).

Exam sample weights should be used for analyses.

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.

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Females only 20 YEARS - 44 YEARS

URXPREG - Pregnancy test result

Variable Name:
SAS Label:
Pregnancy test result
English Text:
Pregnancy test result
Females only 20 YEARS - 44 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Positive 55 55
2 Negative 1094 1149
3 Not done 18 1167
4 Invalid 0 1167
. Missing 0 1167