How much does the uterus matter? Perinatal outcomes are improved when donor oocyte embryos are transferred to gestational carriers compared to intended parent recipients.

ObjectiveTo assess the reproductive and neonatal outcomes of cycles in which donor oocyte embryos were transferred to gestational carriers compared to intended parent recipients.DesignRetrospective cohort study.SettingNot applicable.Patient(s)Intended parent recipients and gestational carriers receiving donor oocyte embryos in 2014 in the United States.Interventions(s)None.Main outcomes measure(s)Clinical pregnancy, live birth, miscarriage, plurality, prematurity, and birth weight from pregnancies conceived with donor oocyte embryos transferred to either a gestational carrier or an intended parent recipient.Result(s)The mean ages of intended parent recipients (N=18,317) and gestational carriers (N=1,927) were 41.6 and 31.6 years, respectively. Compared to an intended parent recipient, patients using a gestational carrier had significantly higher odds of a clinical pregnancy (65.2% vs. 56.3%, adjusted odds ratio (aOR) 1.33, 95% confidence interval (CI) 1.17-1.51) and live birth (57.1% vs. 46.4%, aOR 1.37, 95% CI 1.21-1.55) using fresh or frozen donor-oocyte embryos. Of the singletons born (n=716 using a gestational carrier and n=5,632 in intended parent recipients), the incidence of prematurity was significantly lower in gestational carriers compared to intended parent recipients (17.5% vs. 25.4%, aOR 0.78, 95% CI 0.61-0.99). The incidence of low birthweight among singletons was significantly reduced in gestational carrier cycles (6.4% vs. 12.1%, aOR 0.62, 95% CI 0.44-0.89).ConclusionIntended parent recipients had decreased pregnancy rates and poorer neonatal outcomes compared to a gestational carrier. This suggests that a history of infertility adversely affects the uterine microenvironment, independent of the oocyte.