Marijuana use during and after pregnancy and association of prenatal use on birth outcomes: A population-based study

We sought to describe the correlates of marijuana use during and after pregnancy, and to examine the independent relationship between prenatal marijuana use and infant outcomes.

We used state-specific data from the Pregnancy Risk Assessment Monitoring System (N = 9013) to describe correlates of self-reported prenatal and postpartum marijuana use. We estimated differences in mean infant birth weight and gestational age among prenatal marijuana users and nonusers, controlling for relevant covariates (i.e., cigarette smoking).

Respectively, 4.2% (95% CI: 3.8-4.7) and 6.8% (95% CI: 6.0-7.7) of women reported using marijuana during and after pregnancy. Compared to nonusers, prenatal marijuana users were more likely to be ≤24 years; non-Hispanic white, not married, have <12 years of education, have Medicaid/IHS/Other insurance, be on WIC during pregnancy, have annual household income <$20,000, cigarette smokers, and alcohol drinkers during pregnancy (p-values < 0.05). After adjustment, no differences in gestational age or birthweight were observed. Postpartum users were more likely to smoke cigarettes (48.7% vs. 20.3%), experience postpartum depressive symptoms (14.0% vs. 9.0%), and breastfeed for <8 weeks (34.9% vs. 18.1%).

Co-use of substances was common among prenatal and postpartum marijuana users. Prenatal marijuana use was not independently associated with lower average birthweight or gestational age. Postpartum marijuana use was associated with depressive symptoms and shorter breastfeeding duration. Surveillance of marijuana use among pregnant and postpartum women is critical to better understanding the relationship of marijuana use with birth outcomes, and postpartum experiences such as depression and breastfeeding.