Pregnancy outcomes in women with uterine anomaly: a Swedish nationwide cohort study

INTRODUCTION: Congenital uterine anomalies (UA) result in an increased risk for infertility and miscarriage but there are few population-based studies investigating the prevalence and associations between UA and pregnancy and perinatal outcomes. MATERIAL AND METHODS: This nationwide cohort study includes 599 840 singleton births of primiparas from ≥22 gestational weeks in Sweden between 2010-2022. The risk for adverse pregnancy and perinatal outcomes was compared between women diagnosed with/or treated for UA and those without diagnoses for UA. Logistic regression was used to calculate adjusted odds ratios (aOR) with 95% confidence intervals (CI). RESULTS: There were 1101 (0.2%) women diagnosed with UA. Compared with no UA, UA were associated with an increased risk of preterm birth <34 weeks (aOR 9.10 CI [7.64-10.83]), breech presentation (aOR; 25.46 95% CI [22.59-28.70]), placental abruption (aOR; 5.09 95% CI [3.23-8.03]), emergency caesarean section (aOR: 2.96 [(2.60-3.3]), manual removal of placenta, (aOR:1.73 [1.29-2.33]) and infant small for gestational age (aOR; 2.60 95% CI [(2.11-3.21)]) but not with oligohydramnios, uterine rupture or chorioamnionitis. CONCLUSION: UA was associated with an increased risk of adverse perinatal and intrapartum outcomes, including, preterm birth, infant being small for gestational age, emergency caesarean section and maternal complications including bleeding and manual removal of the placenta. These findings highlight the importance of awareness of these pregnancies in clinical practice to support appropriate monitoring during pregnancy and intrapartum management. KEY MESSAGE: Women with congenital uterine anomalies face substantially higher risks of adverse pregnancy and birth outcomes in a nationwide Swedish cohort of primiparas. These findings add crucial knowledge to guide tailored antenatal and intrapartum care for women with known uterine anomalies.