Prenatal Drug Exposure and Drug-Abusing Environments

Research Findings from September, 1998 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.

High Rate of Passive Exposure to Crack/Cocaine in Infants

Researchers at the Yale Child Study Center prospectively obtained 124 urine samples from 122 children less than one year old for routine clinical indications from the Emergency Department at Yale-New Haven Hospital. Samples were analyzed by radioimmunoassay (RIA) for cocaine, with cross-reactivity for its major metabolite, benzoylecgogine (BE), using a threshold for detection of cocaine and BE that is lower than the current DHHS standard. The presence of cocaine or BE was presumed to indicate passive exposure to crack/cocaine. Of the 124 samples, 36.3 percent were positive (greater than or equal to 50ng/mL BE equivalents) for cocaine and/or BE. The positive samples were highly correlated with lower and upper respiratory symptoms and with seeking medical care more often. Lustbader, A.S., Mayes, L.C., McGee, B.A., Jatlow, P., and Roberts, W.L. Incidence of Passive Exposure to Crack/Cocaine and Clinical Findings in Infants Seen in an Outpatient Service, Pediatrics, (1 Part 1), E5, July 1998.

Prenatal Cocaine Exposure and Stimulus-Seeking Behaviors in Infants

Robert L. Freedland, Ph.D. and colleagues at the New York State Institute for Basic Research, Staten Island, NY, have investigated orientation sensitivity to complex perceptual patterns in groups of normal, brain-injured and cocaine-exposed infants. Previous studies with newborns revealed that normal neonates were able to modulate attention to stimulation depending on their arousal pattern, but brain-injured and cocaine-exposed neonates demonstrated poorer attention modulation. Brain-injured newborns preferred less stimulation even when more aroused (stimulus avoiding) and cocaine-exposed newborns preferred more stimulation even when more aroused (stimulus seeking). Current studies evaluated these differences in older infants (at four and seven months of age), using age-appropriate, complex visual perceptual tasks. These cocaine-exposed infants appear to be most sensitive to oblique orientations presented in a complex, herringbone visual pattern. The inference is that these older cocaine-exposed infants were responding to complex stimuli differently than non-cocaine-exposed, age-matched infants. Novelty responses of cocaine-exposed infants seem to be driven by the orientation of the stimulation-rich elements within the complex visual pattern, which may demonstrate a further instance of arousal-based "stimulation-seeking" behavior. Stimulus-seeking behavior in these older cocaine-exposed infants appeared to continue in development with the more advanced perceptual tasks. These findings are helpful in establishing a basis for the effects of cocaine exposure on infants and for determining if the effects persist. Further, the results suggest differential effects on the development of early sensory organization in cocaine-exposed infants after the first six months of life. The differences in responses to more advanced stimuli with respect to perceptual organization suggest an enduring drug-mediated effect in the sensory encoding of visual information in cocaine pre-exposed infants. Freedland, R.L., Karmel, B.Z., Gardner, J. M., & Lewkowicz, D.J. Prenatal Cocaine Exposure and Stimulus-seeking Behaviors during the First Year of Life. Annals of the New York Academy of Sciences, 846, pp. 386-390, 1998.

Differential Cognitive Functioning in 9-12 Years Olds Relative to Prenatal Cigarette and Marijuana Exposure

In an examination of cognitive performance of 131 9-12 year-old children participating in a Carleton University longitudinal study since birth, discriminant function analysis indicated a dose-dependent association between higher prenatal cigarette exposure in utero and lower performance on global intelligence test scores, with the verbal subtests of the intelligence test discriminating maximally among levels of in utero exposure. In contrast, prenatal marijuana exposure was not associated with global intelligence or the verbal subtests, but rather was negatively related to executive function tasks that require impulse control and visual analysis/hypothesis testing, and with a number of the intelligence subtests requiring these same abilities. The cigarette results extend observations made in this sample and others at earlier ages. The marijuana findings, combined with results observed at earlier ages, lead the authors to suggest that in utero exposure to marijuana may have a negative impact on aspects of neurocognitive competence that fall under the domain of executive function. Fried, P.A., Watkinson, B.M. and Gray, R. Neurotoxicology and Teratology, 20 (3), pp. 293-306, 1998.

The Impact of Maternal Drinking During and After Pregnancy on the Drinking of Adolescent Offspring

The impact of prenatal maternal drinking on alcohol consumption in adolescent offspring was examined among boys and girls separately. A prospective longitudinal sample of 185 mother-firstborn child dyads was used to examine the impact of maternal self-reported lifetime and current drinking, controlling for potential confounding factors. In this representative general population sample, maternal drinking during pregnancy, particularly continuous moderate to heavy consumption, had a significant positive effect on adolescent daughters' current drinking, but a slight negative effect on sons' lifetime drinking. The sex-specific prenatal effect on current drinking persisted with controls for prenatal maternal cigarette smoking, current maternal drinking, child-rearing practices (i.e. maternal child closeness, monitoring and a rule against drinking) and adolescent's problem behaviors in childhood. Prenatal maternal smoking was also associate with elevated rates of adolescent drinking, particularly current drinking. Of the child-rearing variables, only a rule against drinking decreased adolescent drinking. Thus, selected prenatal factors may constitute risks for alcohol consumption among adolescent daughters. Griesler, P.C., Kandel, D.B. Journal of Studies on Alcohol, 59(3), pp. 292-304, 1998.

Maternal Smoking in Pregnancy, Child Behavior Problems, and Adolescent Smoking

This study used a longitudinal sample of mother-child dyads to examine the role of child behavior problems in explaining the effect of maternal prenatal smoking on adolescent daughter's smoking. Maternal smoking during pregnancy is associated with higher levels of child behavior problems, particularly among girls. Childhood behavior problems increase the likelihood of lifetime smoking among daughters but do not explain the effect of prenatal maternal smoking on their current smoking. Maternal smoking in pregnancy, especially heavy use of a pack or more a day, retains a unique effect on girls' current smoking with controls for current maternal smoking, child behavior problems, and maternal monitoring of the child. The effect of maternal prenatal smoking is suggestive of a biological component, which may have direct or indirect influences on adolescent smoking. The small number of cases in the study calls for the replication of these findings in large samples that would incorporate prospective measures of prenatal nicotine exposure from mother and father and additional biological and psychosocial covariates. Griesler, P.C., Kandel, D.B., Davies, M. Journal of Research on Adolescence, 8(1), pp. 159-185, 1998.

Drug Use and Parenting in Adolescence

This project at the University of Washington conducted longitudinal analyses of 241 adolescent mothers' use of 3 substances -- marijuana, alcohol and tobacco -- from the time of pregnancy through 1 year post-partum. Variables measured for each substance included use, verified with urinalysis; intentions to use; attitudes and perceived norms about using; and specific outcome and normative expectations about use of each substance. Substance use increased dramatically from pregnancy to 6 months post-partum, leveling off between 6 and 12 months post-partum. Consistent with the Theory of Reasoned Action model, as substance use increased after pregnancy, so did intentions to use, favorable attitudes toward use, perceived norms regarding use, and beliefs favorable to use. Changes in specific outcome and normative beliefs were observed and that, over time, the young mothers saw bad outcomes of using substances (such as negative effects on their health) as less likely, and positive outcomes (such as helping them to forget their problems) as more likely. They also perceived less disapproval from their families, friends, and doctors after their babies were born. These findings suggest that young mothers are heeding warnings about the danger to their babies of using substances during pregnancy, but are less convinced that substance use has negative effects on parenting or on their own health. The contrast between the abundance of messages warning about substance use during pregnancy and the very few messages aimed at reduce substance use among parents may unwittingly reinforce a notion that substance use is not very harmful when one is not pregnant. A promising intervention approach for young mothers may be to capitalize on their concerns for their babies' health. Morrison, D.M., Spencer, M.S., and Gillmore, M.R. J. Res. Adoles., 8, pp. 69-95, 1998.

Beliefs About Substance Use Among Pregnant and Parenting Adolescents

Substance use among pregnant and parenting adolescents has health implications for both mother and baby. Utilizing the Theory of Reasoned Action, a social psychological model, this research investigates the cognitive structure underlying substance use, based on longitudinal analyses of data from 3 waves of interviews with a cohort of young mothers who were 17 years old or younger during pregnancy. Use of cigarettes, alcohol, and marijuana were lowest during pregnancy, increased sharply at 6 months postpartum, and remained level at 12 months postpartum. Changes in intentions, attitudes, perceived social norms, outcome beliefs, and normative beliefs followed the same pattern. The content of changing beliefs about substance use is examined and implications for substance use interventions among postpartum adolescent mothers is discussed. Morrison, D., Spencer, M., and Gillmore, M. J. Res. Adoles., 8(1), pp. 69-95, 1998.