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

Objective: To compare pregnancy risks between different congenital uterine anomalies utilizing other congenital anomalies as a control group in a large population database.

Design, Setting, And Sample: 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.

Main Outcome Measures And Results: After adjustment for confounders, women with bicornuate uteri were more likely to deliver vaginally (aOR 1.4, 95%CI: 1.1-1.9),  = .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,  = .03) when compared to the other anomalies (aOR 0.6, 95%CI: 0.5-0.6,  = .0001). Pregnant women with arcuate uterus had lower risks of preterm delivery (PTD) (aOR 0.6, 95%CI: 0.5-0.8,  = .0001), less chance of operative vaginal delivery (aOR 0.5, 95%CI: 0.2-0.9,  = .04), and higher risk for CD (aOR 1.6, 95%CI: 1.4-2,  = .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,  = .0001), PTD (aOR 1.5, 95%CI: 1.3-1.6,  = .0001), CD (aOR 1.4, 95%CI: 1.2-1.5,  = .0001) and wound complications (aOR 1.6, 95%CI: 1.1-2.4,  = .02). Pregnant unicornuate uteri had increased risks of PTD (aOR 1.4, 95%CI: 1.1-1.6,  = .0001), CD (aOR 2, 95%CI: 1.6-2.5,  = .0001) and of SGA (aOR 1.8, 95%CI: 1.4-2.3,  = .0001). Pregnant septate uteri had higher risk of chorioamnionitis (aOR 1.5, 95%CI: 1.1-2.1,  = .048) and CD (aOR 1.4, 95%CI: 1.2-1.6,  = .0001).

Conclusions: We demonstrated that there are different risks for certain adverse pregnancy and neonatal outcomes in diverse uterine anomalies as compared to the other anomalies.