Cannabis Use During the Perinatal Period in a State With Legalized Recreational and Medical Marijuana: The Association Between Maternal Characteristics, Breastfeeding Patterns, and Neonatal Outcomes.

Objectives: To evaluate state-level prevalence estimates of prenatal and early postnatal cannabis use in a state with legalized medical and recreational marijuana and the association with adverse neonatal outcomes.

Study Design: We conducted a cross-sectional study on 3,207 respondents from the 2014-2015 Colorado Pregnancy Risk Assessment Monitoring System with state-developed questions on cannabis use. Differences in perinatal cannabis use were evaluated according to maternal characteristics, breastfeeding patterns, and pregnancy intendedness. Multiple logistic regression models evaluated the relationship between prenatal cannabis use and adverse neonatal outcomes including low birth weight, small for gestational age, preterm birth, and admission to the neonatal intensive care unit.

Results: The self-reported prevalence of cannabis use at any time during pregnancy was 5.7 ± 0.5% and the prevalence of early postnatal cannabis use among women who breastfed was 5.0% (95% CI, 4.1%-6.2%). Prenatal cannabis use was associated with a 50% increased likelihood of low birth weight, independent of maternal age, race/ethnicity, level of education, and tobacco use during pregnancy (OR, 1.5; 95% CI, 1.1-2.1; P = .02). Small for gestational age, preterm birth, and neonatal intensive care unit admission were not associated with prenatal cannabis use, independent of prenatal tobacco use.

Conclusions: Our findings underscore the importance of screening for cannabis use during prenatal care and the need for provider counselling about the adverse health consequences of continued use during pregnancy and lactation.