This page reviews existing peer-reviewed clinical and public health research regarding marijuana use during pregnancy and its effects on pregnancy outcomes, neonatal characteristics, and cognitive and developmental performance of offspring at various stages throughout childhood and adolescence. (For a comprehensive, objective analysis of the subtle impact of prenatal cannabis exposure, see Dr. Peter A. Fried’s 2002 article, “The Consequences of Marijuana Use During Pregnancy: A Review of the Human Literature.“) The majority of this literature reports findings from two long-term ongoing cohort studies in North America: the Ottawa Prenatal Prospective Study (OPPS), which began in 1978, and the Maternal Health Practices and Child Development Project (MHPCD) in Pittsburgh, which began in 1982. This analysis also includes studies carried out since 1988 with additional cohorts of pregnant mothers from the United Kingdom, Brazil, Denmark, Jamaica, and the U.S.
Several factors complicate the task of assessing the clinical impact of prenatal marijuana exposure. The relationship between prenatal marijuana exposure and outcome measures such as low birth weight, gestational age, child hyperactivity, depression, school performance, IQ, and behavioral problems is potentially confounded by many demographic factors, such as socioeconomic status, race, maternal age, maternal education, prenatal care, tobacco exposure, alcohol exposure, polydrug exposure, home environment, school attendance, and more. While some researchers attempted to control for these and other factors, others did not include confounding factors in their analyses. Studies varied in their classification of frequency of use (i.e., amount of daily joints, or ADJ, versus “light” or “heavy” marijuana use) and in their reliance on self-reports or on confirmed toxicology results. Though pregnancy outcomes can be measured using fairly straightforward methods (birth weight, birth length, head circumference, gestational age), a wide variety of instruments were used to assess cognitive performance.
Finally, most studies performed in the United States (including OPPS and MHPCD) are at least partially funded by the National Institute on Drug Abuse (NIDA), a federal government agency that has a policy of funding only research focused on the negative consequences of marijuana use. NIDA has refused to fund or supply some FDA-approved research protocols proposing to study the benefits of marijuana, effectively stifling scientific inquiry and manipulating the range of possible findings in this field.
Studies on Pregnancy Outcomes and Neonatal Period
- Bailey, B.A. et al. (2012). Infant birth outcomes among substance using women: Why quitting smoking during pregnancy is just as important as quitting illicit drug use. Maternal and Child Health Journal, 16(2), 414-22. (free full text available)
- Balle, J., Olofsson, M.J., & Hilden, J. (1999). Cannabis and pregnancy. Danish Medical Journal, 161(36), 5024-28.
- Carvalho de Moraes Barros, M. et al. (2006). Exposure to marijuana during pregnancy alters neurobehavior in the early neonatal period. Journal of Pediatrics, 149, 781-87.
- Cornelius, M.D. et al. (1995). Prenatal tobacco and marijuana use among adolescents: Effects on offspring gestational age, growth, and morphology. Pediatrics, 95(5), 738-43.
- David, A.L. et al. (2014). A case-control study of maternal periconceptual and pregnancy recreational drug use and fetal malformation using hair analysis. PLoS ONE, 9(10), e111038. (free full text available)
- Day, N.L. et al. (1991). Prenatal marijuana use and neonatal outcome. Neurotoxicology & Teratology, 13(3), 329-34.
- Day, N.L. & Richardson, G.A. (1991). Prenatal marijuana use: epidemiology, methodologic issues, and infant outcome. Clinics in Perinatology, 18(1), 77-91.
- Desai, A., Mark, K., & Terplan, M. (2014). Marijuana use and pregnancy: Prevalence, associated behaviors, and birth outcomes. Obstetrics & Gynecology, 123, 46S.
- Dreher, M. C., Nugent, K., & Hudgins, Rebekah. (1994). Prenatal marijuana exposure and neonatal outcomes in Jamaica: an ethnographic study. American Academy of Pediatrics, 93(2), 254-260.
- English, D.R. et al. (1997). Maternal cannabis use and birth weight: A meta-analysis. Addiction, 92(11), 1553-60.
- Fergusson, D.M. et al. (2002). Maternal use of cannabis and pregnancy outcome. British Journal of Obstetrics & Gynecology, 109, 21-27.
- Forrester, M.B. & Merz, R.D. (2007). Risk of selected birth defects with prenatal illicit drug use, Hawaii, 1986-2002. Journal of Toxicology & Environmental Health, 70(1), 7-18.
- Fried, P.A., Watkinson, B., & Willan, A. (1984). Marijuana use during pregnancy and decreased length of gestation. American Journal of Obstetrics & Gynecology, 150(1), 23-27.
- Hatch, E.E. & Bracken, M.B. (1986). Effect of marijuana use in pregnancy on fetal growth. American Journal of Epidemiology, 124(6), 986-93.
- Hayes, J.S., Dreher, M.C., & Nugent, J.K. (1988). Newborn outcomes with maternal marihuana use in Jamaican women. Pediatric Nursing, 14(2), 107-10. (free full text available)
- Hurd, Y.L. et al. (2005). Marijuana impairs growth in mid-gestation fetuses. Neurotoxicology & Teratology, 27(2), 221-29.
- Ostrea, E.M., Ostrea, A.R., & Simpson, P.M. (1997). Mortality within the first 2 years in infants exposed to cocaine, opiate, or cannabinoids during gestation. Pediatrics, 100(1), 79-83.
- Schempf, A.H. & Strobino, D.M. (2008). Illicit drug use and adverse birth outcomes: Is it drugs or context? Journal of Urban Health, 85(6), 858-73.
- Shiono, P.H. et al. (1995). The impact of cocaine and marijuana use on low birth weight and preterm birth: A multicenter study. American Journal of Obstetrics & Gynecology, 172(1), 19-27.
- Sundram, S. (2006). Cannabis and neurodevelopment: Implications for psychiatric disorders. Human Psychopharmacology, 21, 245-54.
- Van Gelder, M.M. et al. (2010). Characteristics of pregnant illicit drug users and associations between cannabis use and perinatal outcome in a population-based study. Drug and Alcohol Dependence, 109(1-3), 243-47.
- Witter, F.R. & Niebyl, J.R. (1990). Marijuana use in pregnancy and pregnancy outcome. American Journal of Perinatology, 7(1), 36-38.
- Zuckerman, B. et al. (1989). Effects of maternal marijuana and cocaine use on fetal growth. New England Journal of Medicine, 320, 762-68.
Studies on Cognitive & Behavioral Outcomes
- Dahl, R.E. et al. (1995). A longitudinal study of prenatal marijuana use: Effects on sleep and arousal of age 3 years. Archives of Pediatric & Adolescent Medicine, 149(2), 145-50.
- Day, N.L. et al. (1994). Effect of prenatal marijuana exposure on the cognitive development of offspring at age three. Neurotoxicology and Teratology, 16(2), 169-75.
- Day, N.L., Leech, S.L., & Goldschmidt, L. (2011). The effects of prenatal marijuana exposure on delinquent behaviors are mediated by measures of neurocognitive functioning. Neurotoxicology and Teratology, 33(1), 129-36.
- Fried, P.A. (2002). Conceptual issues in behavioral teratology and their application in determining long-term sequelae of prenatal marijuana exposure. Journal of Child Psychology & Psychiatry, 43(1), 81-102.
- Fried, P.A., James, D.S., & Watkinson, B. (2001). Growth and pubertal milestones during adolescence in offspring prenatally exposed to cigarettes and marihuana. Neurotoxicology & Teratology, 23(5), 431-36.
- Fried, P.A., O’Connell, C.M., & Watkinson, B. (1992). 60 and 72-month follow-up of children prenatally exposed to marijuana, cigarettes, and alcohol: Cognitive and language assessment. Developmental & Behavioral Pediatrics, 13(6), 227-36.
- Fried, P.A., Watkinson, B., & Gray, R. (1992). A follow-up study of attentional behavior in 6-year-old children exposed prenatally to marihuana, cigarettes, and alcohol Neurotoxicology & Teratology, 14(5), 299-311.
- Goldschmidt, L. et al. (2004). Prenatal marijuana and alcohol exposure and academic achievement at age 10. Neurotoxicology & Teratology, 26(4), 521-32.
- Goldschmidt, L. et al. (2008). Prenatal marijuana exposure and intelligence test at age 6. Journal of the American Academy of Child & Adolescent Psychiatry, 47, 254-63.
- Goldschmidt, L. et al. (2012). School achievement in 14-year-old youths prenatally exposed to marijuana. Neurotoxicity and Teratology, 34(1), 161-67. (free full text available)
- Goldschmidt, L., Day, N.L., & Richardson, G.A. (2000). Effects of prenatal marijuana exposure on child behavior problems at age 10. Neurotoxicology & Teratology, 22(3), 325-36.
- Gray, K.A. et al. (2005). Prenatal marijuana exposure: Effect on child depressive symptoms at ten years of age. Neurotoxicology & Teratology, 27(3), 439-48.
- Hayes, J.S. et al. (1991). Five-year follow-up of rural Jamaican children whose mothers used marijuana during pregnancy. West Indian Medical Journal, 40(3), 120-23.
- Huizink, A.C. & Mulder, J.H. (2006). Maternal smoking, drinking or cannabis use during pregnancy and neurobehavioral and cognitive functioning in human offspring. Neuroscience & Biobehavioral Reviews, 30, 24-41. (free full text available)
- O’Connell, C.M. & Fried, P.A. (1991). Prenatal exposure to cannabis: A preliminary report of postnatal consequences in school-age children. Neurotoxicology & Teratology, 13(6), 631-39.
- Richardson, G.A. et al. (2002). Prenatal alcohol and marijuana exposure: Effects on neuropsychological outcomes at 10 years. Neurotoxicology & Teratology, 24(3), 309-20.
- Smith, A.M. et al. (2004). Effects of prenatal marijuana on response inhibition: An fMRI study of young adults. Neurotoxicology & Teratology, 26(4), 533-42.
- Smith, A.M. et al. (2006). Effects of prenatal marijuana on visuospatial working memory: An fMRI study in young adults. Neurotoxicology & Teratology, 28(2), 286-95.
- Wang, X. et al. (2006). Discrete opioid gene expression impairment in the human fetal brain associated with maternal marijuana use. The Pharmacogenomics Journal, 6, 255-64. (full free text available)
- Zammit, S. et al. (2009). Maternal tobacco, cannabis and alcohol use during pregnancy and risk of adverse psychotic symptoms in offspring. British Journal of Psychiatry, 195, 294-300. (full free text available)