LAUSR

Abstract Objective: Müllerian anomalies are associated with increased risk of miscarriage, intrauterine growth restriction (IUGR) and preterm birth. While a commonly implicated cause is restricted expansion of endometrial cavity, alternatively it could be due to abnormal placentation. We sought to examine clinical and histopathologic factors associated with preterm delivery in women with Müllerian anomalies. Study design: One hundred and eleven singleton pregnancies in 85 women were analyzed retrospectively. There were 42 pregnancies with bicornaute, 24 with unicornuate, 24 with septate, 19 with didelphys and one each with arcuate and T-shaped uterus. Primary outcomes included gestational age at delivery, placental histopathology, placenta previa and accreta. Results: Twenty-eight (25.2%) of pregnancies were delivered prior to term. Of those, only 14 (50%) were due to preterm labor or preterm premature rupture of membranes (PPROM). Histological evidence of placental malperfusion was present in 22% of all pregnancies and those delivered at an earlier median gestational age [34 (IQR 31–37) vs. 37 weeks (IQR 34–39); P=0.001]. Malperfusion was more common in preterm than in full term births (46% vs. 14%; P=0.04). Conversely, inflammation was not more common in preterm compared to term deliveries (17.9% vs. 16.9%; P=0.89). Five pregnancies had placenta previa, three of which were complicated by accreta. Conclusion: Placental malperfusion, rather than inflammation, was more commonly associated with preterm births in women with uterine anomalies.