Prenatal Drug Exposure and Drug-Abusing Environments

Research Findings from February, 2003 Director's Report

This section lists selected summaries from NIDA funded research projects that investigate the consequences of prenatal drug exposure. The summaries provided were selected from recent issues of the Director's Report to the National Advisory Council on Drug Abuse. For a more comprehensive listing of NIDA funded projects see the Director's Report.

Drug Abuse's Smallest Victims: In Utero Drug Exposure

The social and economic impact of drug use on our global population continues to increase leaving no geographical, social or cultural group untouched. The National Institute on Drug Abuse, in one of the few large surveys of maternal abuse, found that 5.5% of mothers reported taking an illicit substance during gestation. Accurate identification of in utero drug exposure has important implications for the care of the mother and child, but can raise difficult legal issues. Society discourages prenatal care with the infliction of harsh criminal penalties. Maternal drug use during pregnancy can be monitored with urine, sweat, oral fluid and/or hair testing. Detection of in utero drug exposure has traditionally been accomplished through urine testing; however, the window of detection is short, reflecting drug use for only a few days before delivery. Monitoring exposure through testing of alternative matrices, such as neonatal meconium and hair, offers advantages including non-invasive collection and detection earlier in gestation. There are many unresolved issues in monitoring in utero drug exposure that urgently require research. These can be divided into research to definitively differentiate drug exposed and non-drug exposed fetuses, determine the most efficient methods to routinely monitor women's drug use, and determine how these drug test results relate to neonatal and maternal outcomes. Research in this area is difficult and expensive to perform, but necessary to accurately assess drug effects on the fetus. By increasing our understanding of the physiological, biochemical and behavioral effects of gestational drug exposure, we may ultimately provide solutions for better drug prevention, treatment and a reduction in the number of drug-exposed children. Huestis, M.A. and Choo, R.E. Forensic Science International, 128, pp. 20-30, 2002.

Prenatal Drug Exposure: Early Developmental Effects

Findings from the Maternal Lifestyle Study (MLS) show that prenatal cocaine effects at 1 month of age are detectable and subtle. In addition, the analyses demonstrate that the effects of other drugs (opiates, alcohol, marijuana) can also be observed in the context of a polydrug use model. The sample consisted of 658 exposed and 730 comparison infants matched on race, gender, and gestational age. Sites were located in Detroit, Memphis, Miami, and Providence. Cocaine exposure was related to lower arousal, poorer quality of movement and self-regulation, higher excitability, more hypotonia, and more nonoptimal reflexes, with most effects maintained after adjusting for covariates. Some acoustic cry characteristics, reflecting reactivity, respiratory, and neural control of the cry sound were also compromised by prenatal drug exposure (cocaine, opiates, alcohol, and marijuana). The researchers emphasize that the effects are subtle, i.e., reliable but small differences between the groups, not necessarily clinically significant deficits. However, the authors also emphasize that these subtle differences suggest neurobehavioral vulnerability that may be exacerbated by the caregiving environment, with the resulting potential to develop into deficits. In addition, there are long-term implications of the findings (e.g., cocaine may affect areas of the brain with consequences not likely to be seen until school age and beyond). Long-term follow-up is necessary for determining whether these subtle differences develop into clinically significant deficits. Lester, B.M., Tronick, E.Z., LaGasse, L, et al. The Maternal Lifestyle Study: Effects of Substance Exposure During Pregnancy on Neurodevelopmental Outcome in 1-Month-Old Infants. Pediatrics, 110, pp. 1182-1192, 2002.

Prenatal Cocaine Exposure and Child Language Functioning to 7 Years of Age

Dr. Emmalee Bandstra and colleagues at the University of Miami have reported new findings indicating a stable cocaine-specific effect on indicators of language functioning during early childhood through 7 years of age. Language functioning was assessed at ages 3, 5, and 7 years of age. The sample included 443 children (236 prenatally-exposed to cocaine, and 207 not exposed to cocaine). Longitudinal Generalized Linear Model and Generalized Estimating Equations (GLM/GEE) analyses indicated an association between prenatal cocaine exposure and deficits (i.e., about 1/5 standard deviation) in total language standard scores, after controlling statistically for gender of child; visit age; prenatal exposure to alcohol, marijuana, and tobacco; and over 20 potentially confounding medical and sociodemographic covariates. The researchers report that the link from prenatal cocaine exposure to later language deficits does not appear to be mediated by cocaine-associated deficits in birth weight, length, or head circumference. Bandstra, E.S., Morrow, C.E., Vogel, A.L., et al. Neurotoxicology and Teratology, 24, pp. 297-308, 2002.