Prenatal Drug Exposure and Drug-Abusing Environments

Research Findings from May, 2001 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.

Neurobehavioral Outcomes of Cocaine-Exposed Infants

Singer et al. investigated the neurobehavioral outcomes associated with prenatal cocaine exposure. The sample included 319 infants (158 cocaine-exposed and 161 non-exposed) with a mean-corrected age of 43 weeks post-conception. Cocaine exposure was determined by a positive response to one of the following: infant meconium, urine or maternal urine positive for cocaine; maternal report to hospital staff, or; maternal self-report during clinical interview. Cocaine positive infants were further divided into heavy and light categories. When only cocaine-exposed and non-exposed infants were compared, the exposed infants exhibited significantly more abnormalities in movement and tone than the non-exposed, with a trend for greater jitteriness in the exposed infants. When the exposed group of infants was divided into those with heavy and light exposure, heavily exposed infants had significantly more attentional abnormalities and jitteriness than the lightly exposed and non-exposed groups. Heavily exposed infants were also more likely to be identified with any abnormality than non-exposed infants, had more movement and tone abnormalities and sensory asymmetries than non-exposed infants and were four times as likely to be jittery and nearly twice as likely to demonstrate any abnormality than lightly- and non-exposed infants. Singer, L.T., Arendt, R., Minnes, S., Farkas, K., and Salvator, A. Neurobehavioral Outcomes of Cocaine-Exposed Infants. Neurotoxicology and Teratology, 22(5), pp. 653-666, 2000.

Effects of Prenatal Cocaine/Crack and Other Drug Exposure on Electroencephalographic Sleep Studies at Birth and One Year

Electroencephalographic (EEG) sleep patterns can be used to assess cerebral maturation and neurophysiologic organization of the developing central nervous system. Scher and colleagues conducted sleep studies of infants born to 37 women who used crack or one or more lines per day of powder cocaine during the first trimester of pregnancy. A control group of 34 infants had mothers who used neither cocaine nor crack during pregnancy. Maternal substance use was determined by self-report during interviews. Infants were eligible if they had gestations from 38-42 weeks, no general anesthesia, and 5 minute Apgar scores of >5. A total of 71 infants received 2 hour EEG sleep recordings at 24-36 hours after birth, with 57 infants returning for EEG sleep recordings at 1 year postpartum. The results indicated that after controlling for the significant covariates, prenatal cocaine exposure was associated with less well-developed spectral correlations between homologous brain regions at birth, and with lower spectral EEG power values at 1 year of age. Implications of these findings are that the neurotoxic effects of prenatal cocaine/crack use can be detected with quantitative EEG measures. Further research is needed to determine whether the abnormal brain patterns detected are associated with developmental abnormalities. Scher, M.S., Richardson, G.A., and Day, N.L. Effects of Prenatal Cocaine/Crack and Other Drug Exposure on Electroencephalographic Sleep Studies at Birth and One Year, Pediatrics, 105(1 Pt 1), pp. 39-48, 2000.

Identifying Prenatal Exposure to Illicit Drugs Using Meconium Testing and Maternal Self-Report

In the four-site Maternal Lifestyle Study (Detroit, Miami, Memphis, Providence) of in utero cocaine and/or opiate exposure, meconium specimens of 8,527 newborns were analyzed by immunoassay (EMIT) with GC/MS (gas chromatography/mass spectrometry) confirmation. Maternal self-report of drug use during pregnancy was determined during a hospital interview. Recruitment occurred between May 1993 and May 1995. Prevalence and observed metabolites showed considerable variation across the four sites, and exposure status was higher in low birth weight infants. Results indicated that accurate identification of exposure is likely to be improved with GC/MS confirmation and when the meconium testing is used in conjunction with a maternal hospital interview (e.g., 254 mothers denied use but their infants had positive meconium confirmation for cocaine/opiates, thus allowing identification of an additional 38% of the cocaine/opiate exposed infants by means of meconium testing). Importantly, had the study relied on maternal report only, these 254 infants would have been eligible for inclusion in the unexposed group. However, at the current stage of this new and useful technology, many questions still remain about the disposition of drugs in meconium, and the investigators caution against the use of quantitative analysis of drugs in meconium to estimate the degree of exposure. Lester, B.M., ElSohly, M., Wright, L.L., Smeriglio, V.L., Verter, J., Bauer, C.R., Shankaran, S., Bada, H.S., Walls, H.C., Huestis, M.A., Finnegan, L.P., and Maza, P.L. Pediatrics, 107, pp. 309-317, 2001.

Prenatal Marijuana Exposure - Emerging Theme of Executive Function Deficiencies

In a review of the scientific literature dealing with neurobehavioral consequences of prenatal exposure to marijuana, Fried and Smith identify a degree of consistency in the limited longer-term data that exist, both from cross-sectional reports and from the two available long-term cohort studies, one involving a low-risk sample (Fried, Carleton University) and the other a high-risk sample (Day, University of Pittsburgh). Aspects of executive function appear to be negatively associated with in utero cannabis beyond the age of 3 years, especially attentional behavior and visual analysis/hypothesis testing. Published data are available for children as old as 12 years of age. In addition, the authors note that in work by the Day research group, on the basis of path analysis, it appeared that poor attentional skills of the child mediated an association between maternal report of child delinquency at age 10 years and prenatal marijuana use. Fried and Smith discuss their literature review findings in the context of the broader research fields of marijuana and prefrontal brain function, and they emphasize the need for further, well-controlled investigations. Fried, P.A. and Smith, A.M. Neurotoxicology and Teratology, 23, pp. 1-11, 2001; Goldschmidt, L., Day, N.L., and Richardson, G.A. Neurotoxicology and Teratology, 22, pp. 325-336, 2000.

Community Level Effects on Prevalence of Substance Use During Pregnancy

Multilevel logistic regression models were used to analyze individual and community correlates of prenatal substance use. This study analyzed a subset of data from the California Perinatal Substance Exposure Study (PSE), the subjects in this study (n=10,611) are the subset of women identified as white, non-Hispanic (n=10,611) and Black/African-American (n=2,669) from the larger multiethnic sample (n=29,494); Latinas were not included in this study. Using census data, the proportion of zip code residences receiving public assistance was attached to each respondent's data in the PSE data file. Analyses showed that, except for alcohol, levels of neighborhood public assistance had an independent, significant effect on prevalence of substance use; increasing levels of neighborhood poverty increased the likelihood of a pregnant woman testing positive. Black women had higher predicted prevalence rates for alcohol and cocaine, while White women had higher predicted risks for tobacco, marijuana, and amphetamines. After controlling for neighborhood public assistance levels, no racial differences were seen in the category overall illicit drug use or opiate use. Future more detailed studies are needed to determine if neighborhood poverty effects on substance use are due to compositional effects, e.g., greater access to drugs, greater overall deviance, etc. or contextual factors, e.g., increased stresses associated with poor housing, lack of social services, etc. Finch, B.K., Vega, W.A., and Koldny, B. Substance Use During Pregnancy in the State of California, USA, Soc. Sci. Med. 52, pp. 571-583, 2001.