Factors influencing adverse perinatal outcomes in pregnancies achieved through use of in vitro fertilization.

To determine the associations of specific components of IVF treatment with abnormal perinatal outcomes. Case-control study. University-based and community-based infertility centers. All viable pregnancies achieved through IVF procedures performed between January 1999 and March 2004. None. Infertility etiology, gonadotropin exposure, embryo manipulation, and quality. Of 455 viable pregnancies identified during the study period, 435 met inclusion criteria. While adjusting for maternal age, race, parity, body mass index, infertility center, and year of IVF procedure, multiple gestations were associated with a 12-fold increased risk of poor perinatal outcome compared to singletons. Ovarian hyperstimulation syndrome significantly increased the risk more than 3-fold (odds ratio = 3.14; 95% confidence interval, 1.08-9.14), while endometrial thickness was found to have a significant protective effect (odds ratio = 0.89; 95% confidence interval, 0.80-0.99). We found no effect of etiology of infertility, dose or type of medication used for stimulation, use of embryo-manipulation techniques, or quality on perinatal outcome. These data confirm and quantify the risk of perinatal morbidity associated with multiple births. After adjusting for multiple births, ovarian hyperstimulation syndrome and suboptimal endometrial development are associated with adverse outcomes in pregnancies achieved through IVF. Our findings suggest that it may be the endometrium rather than the embryo that influences fetal growth and perinatal outcomes after IVF.