Study: Maternal Marijuana Use Not Independently Associated With Adverse Effects In Newborns

St. Louis, MO: The moderate use of cannabis during pregnancy is not an independent risk factor for adverse neonatal outcomes such as low birth weight, according to a literature review published online ahead of print in the journal Obstetrics & Gynecology.

Investigators at the Washington University School of Medicine in St. Louis reviewed outcomes from more than two-dozen relevant case-control studies published between 1982 and 2015. Authors reported: “[M]aternal marijuana use during pregnancy is not an independent risk factor for low birth weight or preterm delivery after adjusting for factors such as tobacco use. There also does not appear to be an increased risk for other adverse neonatal outcomes such as SGA (small for gestational age) and placental abruption once we account for other influencing factors.”

They concluded: “[T]he results of this systematic review and meta-analysis suggest that the increased risk for adverse neonatal outcomes reported in women using marijuana in pregnancy is likely the result of coexisting use of tobacco and other cofounding factors and not attributable to marijuana use itself. Although these data do not imply that marijuana use during pregnancy should be encouraged or condoned, the lack of a significant association with adverse neonatal outcomes suggests that attention should be focused on aiding pregnant women with cessation of substances known to have adverse effects on the pregnancy such as tobacco.”

The paper’s findings are similar to those of a 2010 US Centers for Disease Control-sponsored population-based study that determined, “Reported cannabis use does not seem to be associated with low birth weight or preterm birth.”

For more information, please contact Paul Armentano, NORML Deputy Director, at: Full text of the study, “Maternal marijuana use and neonatal outcomes: A systematic review and meta-analysis,” appears in Obstetrics & Gynecology.