(500) Combined Vaginal-Cesarean Delivery of Twins: National Risk Factors and Trends

Objective: Combined vaginal-cesarean delivery is a known and concerning outcome of trial of labor in twin gestations. We sought to analyze trends in and risk factors for combined vaginal-cesarean twin births during delivery hospitalizations in the United States.

Study Design: This cross-sectional study utilized 2016 to 2020 delivery data from the Nationwide Readmissions Database of women aged 15 to 54 years with monochorionic diamniotic (MCDA) or dichorionic diamniotic (DCDA) twin gestations who had vaginal or combined vaginal-cesarean births. Combined deliveries were ascertained via diagnosis codes for both vaginal and cesarean birth in the same delivery hospitalization. Trends analyses were conducted using joinpoint regression to estimate the average annual percent change (AAPC) with 95% confidence intervals (CI). Adjusted logistic regression models were performed to evaluate the relationship between clinical, hospital, and demographic risk factors and the primary outcome of combined delivery with odds ratios (aOR) expressed as measures of association.

Results: Of 75,591 hospitalizations, 66,952 (88.6%) resulted in vaginal birth of both twins and 8,639 (11.4%) in combined delivery. From 2016 to 2020, the rate of combined deliveries decreased from 12.2% to 10.8% (AAPC -3.0%, 95% CI -4.2, -2.0%), while vaginal twin births increased and cesarean births decreased. Factors associated with elevated odds of combined delivery include advanced maternal age, Medicaid payer, obesity, history of cesarean birth, and placental abruption. Compared to term twins, preterm gestational age at delivery was associated with combined delivery (Table). MCDA gestations were less likely to have a combined delivery compared to DCDA gestations (aOR 0.58, 95% CI 0.52, 0.64).

Conclusion: Combined deliveries decreased over the study period but were the ultimate mode of delivery in over 1 in 10 twin pregnancies. Clinical risk factors associated with combined twin delivery include advanced maternal age, obesity, prior cesarean birth, and preterm gestational age at delivery.