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How common is marijuana use during pregnancy? Marijuana is the most commonly used illicit drug and, after alcohol and tobacco, the most commonly used drug during pregnancy. 2.8% of pregnant women report some use of marijuana during their first trimester. What effects are there from prenatal exposure to marijuana? Growth effects: Research has not found any major effects on growth from marijuana exposure. There have been slight effects reported for: birth weight, head or chest circumference, gestational age, and growth retardation. Behavioral effects: Prenatal exposure to marijuana associated with decreased rates of visual habituation and increased tremors in 4-day-old infants. By 1 year of age, however, no adverse behavioral effects of prenatal marijuana exposure were noted after adjusting for important variables such as ratings of the home environment. Arousal regulation and attention: Prenatal marijuana exposure has an effect on child behavior problems at preschool and school age. Research on 10 year old, prenatally exposed children has shown that 1st and 3rd trimester exposure predicted increased hyperactivity, inattention, and impulsivity symptoms. Among prenatally exposed 13-16 year olds, research has shown decreased attention stability. But, the question remains whether this finding is a true difference or results from lowered parental tolerance. Cognitive effects: Very few studies have been conducted on the cognitive effects of prenatal marijuana exposure. Currently, there has only been one study to measure the link between prenatal marijuana exposure and cognitive functions. The results showed prenatal exposure predicted visual memory, analysis, and integration deficiencies. Social and environmental considerations: It is difficult to isolate the effects of marijuana exposure from other associated drug use and from environmental risk factors such as maternal mental health, exposure to violence, limited access to medical and social services, absence of a male figure in the household, and fewer social support networks; many of which are associated with maternal marijuana use. Future Drug Use Among Offspring: Presently, only one study has been conducted concerning prenatal marijuana exposure and the subsequent usage of cigarettes or marijuana in adolescents (16 to 21-year-olds). This study showed that marijuana use during pregnancy is related to the initiation of cigarette and marijuana use as well as daily cigarette smoking in adolescents. A relationship between the amount of marijuana used during pregnancy and the amount of marijuana and/or cigarettes used by adolescents was also found. However, important factors, such as the effect of exposure to tobacco after birth and parent’s current use of cigarettes or other substances, were not controlled. Thus, future research is greatly needed in order to better establish the effects of prenatal marijuana exposure on adolescents’ drug use. Summary After taking into account maternal personality and home environment
conditions, many neurobehavioral consequences of prenatal exposure
to marijuana do not remain significant.
REFERENCES: Fried, P. A., Watkinson, B., Gray, R. Differential effects of cognitive functioning in 13- to 16-year-olds prenatally exposed to cigarettes and marihuana. Neurotoxicology and Teratology. 25, 427-436, 2003 Fried, P. A., Watkinson, Barbara. Differential effects on facets
of attention in adolescents prenatally exposed to cigarettes and
marihuana. Neurotoxicology and Teratology. 23, 421-430, 2001 Porath, A.J., Fried, P.A. Effects of prenatal cigarette and marijuana exposure on drug use among offspring. Neurotoxicology and Teratology. 27, 267-277, 2005
The Maternal Substance Abuse and Child Development
Study is under the direction of Claire D. Coles Ph.D., with the
Department of Psychiatry and Behavioral Science, Emory University
School of Medicine. For more information, please contact: Claire
D. Coles: ccoles@emory.edu
Karen K. Howell: khowell@emory.edu
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