Cannabis Use During Pregnancy Linked to Preterm Birth

Cannabis use during pregnancy is associated with a significantly higher rate of preterm birth, according to the results of a recent study.

Recent evidence has suggested an increase in the rate of cannabis use during pregnancy, but there is currently limited data regarding perinatal outcomes following in utero exposure.

The researchers conducted a retrospective cohort study involving 661,617 pregnancies among women aged 15 years and older in Ontario, Canada between April 2012 and December 2017.

Overall, 9427 (1.4%) of the women reported cannabis use during pregnancy. The crude rate of preterm birth (less than 37 weeks’ gestation) was 6.1% among women who did not use cannabis and 12.0% among those who did (risk difference [RD] 5.88%). In the matched cohort (5639 users and 92,873 nonusers), cannabis use was significantly associated with preterm birth (RD 2.98% and relative risk (RR] 1.41).

Reported use was significantly associated with greater frequency of being small for gestational age, placental abruption, transfer to neonatal intensive care, and 5-minute Apgar score less than 4.

“Among pregnant women in Ontario, Canada, reported cannabis use was significantly associated with an increased risk of preterm birth. Findings may be limited by residual confounding.”

—Michael Potts

Reference:

Corsi DJ, Walsh L, Weiss D, et al. Association between self-reported prenatal cannabis use and maternal, perinatal, and neonatal outcomes [published online June 18, 2019]. JAMA. doi:10.1001/jama.2019.8734