Maternal Marijuana Use and Childhood Outcomes

Between four and five percent of pregnant women report some level of cannabis use. This level decreases markedly throughout pregnancy. Many women who report using cannabis during pregnancy do so to address symptoms of nausea/morning sickness.

RESOURCES: Cannabis and pregnancy: Maternal child health implications during a period of drug policy liberalization, Preventive Medicine, 2017 | Marijuana use in pregnancy and lactation: A review of the evidence, American Journal of Gynecology & Obstetrics & Gynecology, 2015 | Survey of medicinal cannabis use among childbearing women: patterns of its use in pregnancy and retroactive self-assessment of its efficacy against ‘morning sickness’, Complementary Therapies In Clinical Practice, 2006

Data to date is inconsistent with respect to whether in utero cannabis exposure is independently associated with low birthweight, pre-term birth, or other adverse neonatal outcomes (e.g., shorter gestational age)

• “The aim of this study is to estimate the association between marijuana use during pregnancy and total, spontaneous and indicated preterm birth. … Marijuana use was not associated with total preterm birth in this cohort, suggesting that among women already at high risk of preterm birth, marijuana does not increase risk further.”Marijuana Use during Pregnancy and Preterm Birth: A Prospective Cohort Study, American Journal of Perinatology, 2020

• “This is a retrospective cohort study from July 2016 to December 2018 of pregnant women who had universal drug screening of marijuana use before and after legalization of recreational marijuana in California on 1 January 2018. Maternal medical conditions and neonatal outcomes associated with usage were also evaluated. … There were no differences in neonatal outcomes between users and non-users.”The impact of state legalization on rates of marijuana use in pregnancy in a universal drug screening population, The Journal of Maternal-Fetal & Neonatal Medicine, 2020

• “Compared with babies of mothers who had never used cannabis, infants of those who still used at 15 weeks had lower mean values for birthweight, head circumference, and gestational age at birth.”The deleterious effects of cannabis during pregnancy on neonatal outcomes, The Medical Journal of Australia, 2020

• “Marijuana exposed newborns had significantly worse birth outcomes than controls, weighing less … and more likely to be low birth weight, preterm, or admitted to the NICU.”The impact of pregnancy marijuana use on birth outcomes: Results from two matched population-based cohorts, Journal of Perinatology, 2020

• “A study was carried out in 4465 infants whose mothers delivered during 2017 and 2018. Self-reported maternal smoking, e-cigarette and cannabis use at booking were recorded. Outcome measures were birthweight and head circumference z-scores and admission to the neonatal intensive care unit (NICU). … Cannabis use alone was not associated with a significant reduction in birthweight or head circumference z-score, but the combination of cannabis and cigarette smoking resulted in a significant decrease in both z-scores compared to cigarette smoking alone.”Maternal smoking and cannabis use during pregnancy and infant outcomes, Journal of Perinatal Medicine, 2020

• “[O]verall prevalence of marijuana use during pregnancy was low. … [M]arijuana use during pregnancy was not independently associated with infant birth weight or gestational age, after controlling for confounding. … Further, we did not observe significant effects of marijuana use during pregnancy and preterm birth or healthcare utilization.”Marijuana use during and after pregnancy and association of prenatal use on birth outcomes: A population-based study, Drug and Alcohol Dependence, 2018

In utero cannabis exposure is not independently associated with significant, consistent adverse effects on childhood development

• RESOURCES: Breathe, Push, Puff? Pot Use and Pregnancy: A Review of the Literature, NORML, 2009 | Women and Cannabis: Medicine, Science, and Sociology, Haworth Press, 2002

• “This article provides a critical review of results from longitudinal studies examining the impact of prenatal cannabis exposure on multiple domains of cognitive functioning in individuals aged 0 to 22 years. … The current evidence does not suggest that prenatal cannabis exposure alone is associated with clinically significant cognitive functioning impairments.”Totality of the Evidence Suggests Prenatal Cannabis Exposure Does Not Lead to Cognitive Impairments: A Systematic and Critical Review, Frontiers in Psychology, 2020

• “The evidence base for maternal-infant health outcomes of cannabis use in pregnancy is more robust than for many other substances. … Although there is a theoretical potential for cannabis to interfere with neurodevelopment, human data drawn from four prospective cohorts have not identified any long-term or long lasting meaningful differences between children exposed in utero to cannabis and those not.”Cannabis and pregnancy: Maternal child health implications during a period of drug policy liberalization, Preventive Medicine, 2017

• “Neither maternal nor paternal cannabis use was associated with educational attainment (in their children) in observational analyses, but few mothers in our sample used cannabis regularly in pregnancy.”The effect of in utero exposure to alcohol, tobacco and cannabis on educational attainment in adolescence: findings from ALSPAC, a UK cohort study, Journal of Epidemiology & Community Health, 2017