OBJECTIVE: To evaluate the incidence of preeclampsia after intrauterine insemination (IUI) with either donor's or partner's sperm in women with primary infertility.DESIGN: Retrospective cohort study.SETTING: Tertiary referral center.PATIENTS: Between January 1999 and December 2006, 823 women who achieved pregnancy after IUI and delivered at > or =24 weeks of gestation were reviewed. Only women with primary infertility and no known medical disorders were included. On the basis of the available outcome data, the final analysis was performed in 713 pregnancies (438 pregnancies using donor's sperm and 275 pregnancies using partner's sperm).INTERVENTION(S): None.MAIN OUTCOME MEASURE(S): The incidence of preeclampsia.RESULT(S): The incidence of preeclampsia in pregnancies resulting from donor sperm was higher than in the partner insemination group: 10.9% (48/438) versus 7.2% (20/275), respectively (difference, 3.7; 95% confidence interval -0.8 to +7.8). Logistic regression was performed controlling for the following parameters: type of sperm, number of previous cycles, and number of babies. In the final model, the variables that significantly predicted the risk of preeclampsia were the type of sperm used for insemination and the number of previous IUI cycles performed. The fewer cycles that were performed, the higher the incidence of preeclampsia that was observed.CONCLUSION(S): IUI with donor sperm appears to increase the incidence of preeclampsia when pregnancy is achieved. A protective effect of multiple cycles appears also to be present in this respect.