Cannabis exposure during pregnancy and perinatal outcomes: A cohort study

Introduction: Cannabis potency and its use during pregnancy have increased in the last decade. The aim of this study was to investigate the impact of antenatal cannabis use on fetal growth, preterm birth and other perinatal outcomes.

Material and methods: A propensity score-matched analysis was performed in women with singleton pregnancies attending a tertiary care site in Barcelona. Women in the cannabis group were selected based on the results of a detection test. Primary outcomes were small for gestational age at birth (SGA), low birthweight and preterm birth. Secondary outcomes were other biometric parameters (neonatal length and head circumference), respiratory distress, admission to the neonatal intensive care unit and breastfeeding at discharge. A second propensity score-matched analysis excluding other confounders (use of other recreational drugs and discontinuation of cannabis use during pregnancy) was performed.

Results: Antenatal cannabis was associated with a higher odds ratio of SGA (OR 3.60, 95% CI: 1.68-7.69), low birthweight (OR 3.94, 95% CI: 2.17-7.13), preterm birth at 37 weeks (OR 2.07, 95% CI: 1.12-3.84) and 32 weeks of gestation (OR 4.13, 95% CI: 1.06-16.11), admission to the neonatal intensive care unit (OR 1.95, 95% CI: 1.03-3.71), respiratory distress (OR 2.77, 95% CI: 1.26-6.34), and lower breastfeeding rates at discharge (OR 0.10, 95% CI: 0.05-0.18). When excluding other confounders, no significant association between antenatal cannabis use and SGA was found.

Conclusions: Antenatal cannabis use increases the risk of SGA, low birthweight, preterm birth and other adverse perinatal outcomes. However, when isolating the impact of cannabis use by excluding women who use other recreational drugs and those who discontinue cannabis during pregnancy, no significant association between antenatal cannabis use and SGA birth was found.