The Maternal Lifestyle Study: drug use by meconium toxicology and maternal self-report

The objective of this study was to describe drug use by pregnant women participating in the 4-site Maternal Lifestyle Study of in utero cocaine and/or opiate exposure.

Meconium specimens of 8527 newborns were analyzed by immunoassay with GC/MS confirmation for metabolites of cocaine, opiates, cannabinoids, amphetamines, and phencyclidine. Maternal self-report of drug use was determined by hospital interview.

The prevalence of cocaine/opiate exposure in the 4 sites was 10.7% with the majority (9.5%) exposed to cocaine based on the combination of meconium analysis and maternal self-report. However, exposure status varied by site and was higher in low birth weight infants (18.6% for very low birth weight and 21.1% for low birth weight). Gas chromatography/mass spectrometry (GC/MS) confirmation of presumptive positive cocaine screens was 75.5%. In the cocaine/opiate-exposed group, 38% were cases in which the mother denied use but the meconium was positive. There was 66% agreement between positive meconium results and positive maternal report. Only 2% of mothers reported that they used only cocaine during pregnancy and mothers were 49 times more likely to use another drug if they used cocaine.

Accurate identification of prenatal drug exposure is improved with GC/MS confirmation and when the meconium assay is coupled with a maternal hospital interview. However, the use of GC/MS may have different implications for research than for public policy. We caution against the use of quantitative analysis of drugs in meconium to estimate the degree of exposure. Our study also highlights the polydrug nature of what used to be thought of as a cocaine problem.