What type of uterine anomalies had an additional effect on pregnancy outcomes, compared to other uterine anomalies? An evaluation of a large population database

To compare pregnancy risks between different congenital uterine anomalies utilizing other congenital anomalies as a control group in a large population database.A retrospective population-based cohort study from the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample (HCUP-NIS) included 3,846,342 births (2010-2014). Of them, 6195 deliveries were to women with bicornuate uteri, 798 with arcuate uteri, 2255 with didelphys uteri, 802 with unicornuate uteri and 1404 with septate uteri.After adjustment for confounders, women with bicornuate uteri were more likely to deliver vaginally (aOR 1.4, 95%CI: 1.1-1.9), p = .01), less likely to deliver by cesarean (CD) and had lower risk of small for gestational age (SGA) (aOR 0.8, 95%CI: 0.7-0.9, p = .03) when compared to the other anomalies (aOR 0.6, 95%CI: 0.5-0.6, p = .0001). Pregnant women with arcuate uterus had lower risks of preterm delivery (PTD) (aOR 0.6, 95%CI: 0.5-0.8, p = .0001), less chance of operative vaginal delivery (aOR 0.5, 95%CI: 0.2-0.9, p = .04), and higher risk for CD (aOR 1.6, 95%CI: 1.4-2, p = .0001). Pregnant women with didelphys uteri had higher risk of preterm premature rupture of membranes (PPROM) (aOR 1.6, 95%CI: 1.3-1.9, p = .0001), PTD (aOR 1.5, 95%CI: 1.3-1.6, p = .0001), CD (aOR 1.4, 95%CI: 1.2-1.5, p = .0001) and wound complications (aOR 1.6, 95%CI: 1.1-2.4, p = .02). Pregnant unicornuate uteri had increased risks of PTD (aOR 1.4, 95%CI: 1.1-1.6, p = .0001), CD (aOR 2, 95%CI: 1.6-2.5, p = .0001) and of SGA (aOR 1.8, 95%CI: 1.4-2.3, p = .0001). Pregnant septate uteri had higher risk of chorioamnionitis (aOR 1.5, 95%CI: 1.1-2.1, p = .048) and CD (aOR 1.4, 95%CI: 1.2-1.6, p = .0001).We demonstrated that there are different risks for certain adverse pregnancy and neonatal outcomes in diverse uterine anomalies as compared to the other anomalies.