Key PointsQuestionIs maternal obsessive-compulsive disorder (OCD) associated with adverse pregnancy, delivery, and neonatal outcomes?FindingsIn 2 cohort studies including 10 653 pregnancies to mothers with OCD in Sweden and British Columbia, Canada, maternal OCD was associated with statistically significantly increased risk of adverse pregnancy, delivery, and neonatal outcomes. Sister and cousin analyses showed that at least some of the described associations were independent from familial confounding.MeaningThis study suggests that greater collaboration between psychiatrists and obstetricians and close monitoring of pregnant women with OCD and their newborns is warranted.