We included as donors all women who donated a kidney between July 1, 1992, and April 30, 2010, in Ontario and who had at least one pregnancy with a gestation of at least 20 weeks during follow-up. (The primary outcome was assessed after 20 weeks of gestation.) Each woman’s nephrectomy date served as her cohort-entry date. To assess new events during follow-up, we excluded women in whom gestational hypertension or preeclampsia had been diagnosed before donation (in ≤5 women). We identified a matched set of nondonors for 85 of 88 study-eligible donors, as described below.