Importance: Many studies have evaluated whether in utero cannabis exposure is associated with fetal and neonatal outcomes, yet little is known about whether prenatal cannabis use is associated with maternal health outcomes during pregnancy.

Question: Is prenatal cannabis use associated with maternal health outcomes during pregnancy?

Findings: In this cohort study of 316 722 pregnancies, prenatal cannabis use was associated with increased risk of gestational hypertension, preeclampsia, weight gain greater and less than guidelines, and placental abruption as well as reduced risk of gestational diabetes. No association was found with eclampsia, placenta previa, placenta accreta, or severe maternal morbidity.

Meaning: The results of this study suggest that the association between prenatal cannabis use and maternal health is complex and there is a need for continued research to understand how prenatal cannabis use affects the health of pregnant individuals.