Type of congenital uterine anomaly and adverse pregnancy outcomes.

OBJECTIVE To estimate whether the severity of uterine anomaly is associated with the risk of adverse pregnancy outcomes. METHODS Retrospective cohort study of patients delivered by one maternal fetal medicine group from 2005 to 2012. We included 158 patients with a singleton pregnancy and a uterine anomaly, as well as an equal number of randomly selected unexposed singleton pregnancies delivered by the same group. Patients with uterine anomalies were subdivided into those with major fusion defects (unicornuate, bicornuate and didelphys) and minor fusion defects (arcuate, septate and t-shaped). RESULTS The incidence of adverse pregnancy outcomes increased across unexposed patients, patients with minor fusion defects and patients with major fusion defects. These included preterm birth < 37 weeks, preterm birth < 35 weeks, birth weight < 10th percentile, birth weight < 5th percentile, preeclampsia, malpresentation and cesarean delivery. CONCLUSION The incidence of adverse pregnancy outcomes and cesarean delivery is increased in patients with minor fusion defects and is further increased in patients with major fusion defects.