Reduced live birth rates after embryo transfer in patients with prior cesarean delivery: A retrospective cohort study.

OBJECTIVE

To evaluate whether live birth rates following first embryo transfer (ET) among patients after cesarean delivery are lower compared to patients with only prior vaginal delivery.

STUDY

DESIGN

Retrospective cohort study including patients with prior delivery who underwent first subsequent embryo transfer (fresh or frozen) between January 2013 and September 2019. The primary outcome was live birth rate among patients with at least one prior cesarean delivery compared to vaginal delivery only. Secondary outcomes included positive serum hCG, clinical intrauterine pregnancy and miscarriage rates. We performed a subgroup analysis with the cesarean delivery group based on labour status at the time of delivery. We fit a multivariable log-binomial regression model.

RESULTS

Total of 962 patients met inclusion criteria: 351 in the cesarean delivery group and 611 in the vaginal delivery group. Live birth rate was significantly lower in the cesarean delivery group compared to vaginal delivery group at 30.0% vs 36.9% [aRR 0.81, 95% CI 0.67-0.98]. We also found lower positive hCG [aRR 0.82, 95% CI 0.72-0.94] and clinical pregnancy [aRR 0.85, 95% CI 0.73-0.99]. There was no significant difference in miscarriage rate. A subgroup analysis within the cesarean delivery group in active labour demonstrated significantly lower live birth rates compared to the vaginal delivery group [aRR 0.67, 95% CI 0.49-0.92].

CONCLUSIONS

Live birth rates following first ET were significantly lower after cesarean delivery compared to vaginal delivery. These findings may be largely attributable to a subgroup of patients with prior cesarean delivery in active labour who may be at particular risk of reduced live birth rates after ET.