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National Pregnancy and Health Survey: Drug Use Among Women Delivering Live Births (NPHS-1992)
Parent Series Details:
The primary objective of the National Pregnancy and Health Survey (NPHS) was to produce national annual estimates of the percentages and numbers of mothers of live newborns in the United States who used selected licit and illicit drugs in the 12 months prior to delivery. A further objective was to describe patterns of prenatal substance use among demographic subgroups of women. Information on demographic and socioeconomic characteristics, obstetric history, and drug treatment of women who delivered infants at sampled hospitals was obtained through an interviewer-administered questionnaire, while data on substance use before and during pregnancy were collected through a questionnaire completed by the respondent and concealed from the interviewer. Respondents were asked about use of the following substances: alcohol, amphetamines, analgesics, cocaine, crack cocaine, barbiturates, hallucinogens, hashish, heroin, marijuana, methadone, methamphetamine, sedatives, stimulants, tobacco, and tranquilizers. Additionally, information was collected on the respondent's pregnancy, prenatal care, delivery, previous pregnancies, and background. Additional data were obtained from the mothers' and infants' medical records. Urine specimens collected routinely by the hospital on obstetric admissions were tested for selected drugs. Finally, in a subsample of six hospitals, hair specimens were requested from respondents to evaluate the potential of hair as a source of toxicological data in future studies.
Geographic coverage :
Unit of observation:
Women delivering live-born infants in hospitals in the contiguous 48 states with 200 or more births per year.
Data were collected by Westat, Inc.
To protect the anonymity of respondents, all variables that could be used to identify individuals have been collapsed, recoded, or removed from the public use file. These modifications should not affect analytic uses of the public use file.
- demographic characteristics
- drug testing
- drug treatment
- drug use
- economic indicators
- live births
- prenatal care
- reproductive history
- tobacco use
A two-staged sampling procedure within strata was used, with selection of hospitals in the first stage and selection of mothers within the sampled hospitals in the second stage. The sampling frame for hospitals included all hospitals in the contiguous United States with 200 or more births per year. Hospitals were stratified by (1) metropolitan area hospitals in counties with high concentrations of Hispanics, (2) other metropolitan hospitals, and (3) nonmetropolitan hospitals. Hospitals were selected with probability proportionate to size using the number of births in 1989 as a measure of size. The final sample consisted of 37 hospital clusters containing 60 individual hospitals.
When a survey design incorporates clustering and differential sampling of some subpopulations, variance estimates that assume a simple random sample design can substantially underestimate the true variability of the sample estimates. For the NPHS the variability of the sample estimates was estimated using jackknife replication (option JK2 in WesVarPC) using the full sample weight TRMADJMW and the following eighteen (18) replicate weights: TADJ1 to TADJ18. If infant estimates are desired, each of these weights (including the full sample weight) should be multiplied by the variable NUMBABES. These procedures allowed all aspects of the complex sample design including the weighting process to be reflected in the estimated standard errors.
- The response rate among the 60 hospitals originally sampled was 65 percent (39 hospitals). Of the 21 hospitals that refused participation, 13 were replaced following specific substitution rules. Eight hospitals refused participation and were not replaced, for a final sample of 52 hospitals. Mothers were randomly selected from within the participating hospitals. Of the 3,386 mothers sampled for the survey, 1 percent (46) were found to be ineligible. These were women who spoke neither English nor Spanish. Of the 3,340 eligible mothers, 89 percent (3,007) could be approached (i.e., the hospital allowed them to be contacted). Of all eligible respondents, 2,613 completed the questionnaire on substance use. This was 78 percent of the those eligible and 87 percent of those approached. Mothers' and infants' medical records were abstracted for 92 percent of the women who completed the substance use questionnaire.
- 2008-07-31: New files were added. These files included one or more of the following: Stata setup, SAS transport (CPORT), SPSS system, Stata system, SAS supplemental syntax, and Stata supplemental syntax files, and a tab-delimited ASCII data file. Some other minor edits were made to improve the data and documentation.
Extent of processing:
- Performed consistency checks.
- Created variable labels and/or value labels.
- Standardized missing values.
- Created online analysis version with question text.
- Performed recodes and/or calculated derived variables.
- Checked for undocumented or out-of-range codes.