P-718 How do bicornuate uteri alter pregnancy, intra-partum and neonatal risks? A population based study of more than 3-million deliveries and more than 6000 bicornuate uteri
Authors: Badeghiesh A , Kadour E , Baghlaf H , Dahan M.H 
Published: June 2022

Study question

What are the obstetrical outcomes in the third-trimester in women with bicornuate uteri based on analysis of the Healthcare-Cost and Utilization Project-Nationwide Inpatient Sample(HCUP-NIS)database?

Summary answer

Bicornuate uteri increased risks in pregnancy. Notably risks of premature-delivery, Cesareans, PPROM, placental-abruption, hysterectomy, SGA and IUFD were increased 250%-500%.

What is known already

Bicornuate uterus is the most frequent uterine malformation. Previous individual studies were mostly small and yielded conflicting results regarding the effect of bicornuate uterus on pregnancy outcomes. In a recent systematic review of all congenital anomalies, 124 pregnancies with bicornuate uteri were included, and it was associated with increased rates of first-trimester miscarriage preterm birth, and fetal malpresentation.

Study design, size, duration

This retrospective population-based cohort study utilizing data from the Healthcare-Cost and Utilization Project-Nationwide Inpatient Sample (HCUP-NIS) from 2010 to 2014, inclusive. There were 3,846,342 births between 2010 and 2014, included in the study. Six thousand and one hundred ninety five deliveries were to women with bicornuate uterus, and the remaining deliveries without other uterine anomalies were categorized as the reference group (n = 3,840,147).

Participants/materials, setting, methods

HCUP-NIS is the largest inpatient database in the USA and is comprised of hospitalizations throughout the USA. It provides information relating to seven-million inpatient stays yearly, includes 20% of admissions, and represents over 96% of the Americans. Multivariate logistic regression, was conducted to explore associations between bicornuate uteri and delivery outcomes and control for confounding effects. According to the Tri-Council Policy Statement (2018), IRB approval was not required, given data was anonymous and publicly available.

Main results and the role of chance

Pregnant women with bicornuate uteri were older and more likely to be obese (P = 0.0001) with previous CD (31% vs. 17.1%, P = 0.0001). After adjustment for confounders, they were more likely to experience pregnancy-induced HTN (aOR 1.21, 95%CI: 1.1-1.3, P = 0.0001), preeclampsia (aOR 1.4, 95%CI: 1.2-1.6, P = 0.0001) and placenta previa (aOR 1.7, 95%CI: 1.3-2.2, P = 0.0001). Moreover, women with bicornuate uterus were more likely to deliver preterm (aOR 2.8, 95%CI: 2.6-3.1, P = 0.0001), deliver by CD (aOR 5, 95%CI: 3.1-4.1, P = 0.0001), experience PPROM (aOR 3.5, 95%CI: 2.6-3.1,P=0.0001), and have a placental abruption (aOR 3.0, 95%CI: 2.5-3.5, P = 0.0001). There were increased risks of PPH (aOR 1.4, 95%CI: 1.2-1.6, P = 0.0001), wound-complications (aOR 2.0, 95%CI: 1.5-2.7, P = 0.0001), hysterectomy (aOR 2.6, 95%CI: 1.6-4.1, P = 0.0001), blood-transfusion (aOR 1.7, 95%CI: 1.5-2.1, P = 0.0001), and DIC(aOR 1.6, 95%CI: 1.1-2.5), P = 0.014) in the group with bicornuate uteri. Pregnant women with bicornuate uterus had a higher risk of SGA (aOR 2.9, 95%CI: 2.6-3.2, P = 0.0001) and IUFD (aOR 2.5, 95%CI: 1.8-3.3, P = 0.0001). There was no increased risk for chorioamnionitis (P = 0.47) or maternal infection (P = 0.8) in women with bicornuate uteri.

Limitations, reasons for caution

This is a retrospective analysis utilizing an administrative database that relies on data coding accuracy and consistency.

Wider implications of the findings

The present study demonstrates that women with bicornuate uteri tend to deliver preterm, by CD, and with increased probability of PPROM or abruption placenta. Neonatal outcomes were also worse in women with bicornuate uteri including a 250%-300% increase in the risk of SGA and IUFD.

Trial registration number

Not Applicable