Predictors of a successful external cephalic version: a population-based cohort study

External cephalic version (ECV) corrects breech presentation and improves vaginal delivery success rate.

To investigate factors influencing ECV success in breech-presenting pregnant women in southern China.

A total of 484 pregnant women who underwent ECV from August 2021 to August 2023 were enrolled. Logistic regression analyzed factors associated with ECV success, and restricted cubic spline (RCS) evaluated relationships of amniotic fluid index (AFI) and gestational weight gain with ECV success.

In all ECV, the success rate was 75.41%. Logistic analysis showed that pregnancy weight gain was a risk factor for ECV, and the success rate decreased with weight increase, OR = 1.05(1.01, 1.09). Shallow into the basin of the fetal breech was a protective factor for ECV, OR (95%CI) = 0.10(0.03, 0.33) compared with not into the basin. Single nuchal cord can increase the probability of ECV success compared with no nuchal cord (OR (95%CI) = 0.43(0.20, 0.91)). The success gradually increases with AFI's rise, OR (95%CI) = 0.06 (0.01, 0.23). RCS analysis revealed non-linear relationships between ECV success and AFI, as well as between ECV success and pregnancy weight gain. ECV success rate increased with AFI within the range of 13.2-17.0 cm. And for pregnancy weight gain, the success rate increased within 5.5-12.0 kg but decreased when weight gain was 12.0-20.0 kg.

Excessive pregnancy weight gain can reduce the success rate of ECV, while AFI, shallow into the basin, and single nuchal cord are protective factors. Non-linear relationships exist between gestational weight gain, AFI, and ECV success. Clinically, these findings advise women to monitor AFI around 13.2-17.0 cm and control weight gain within 5.5-12.0 kg after 28weeks to improve ECV success.