Association of external cephalic version before term with late preterm birth

Area of Science:

• Maternal-fetal medicine
• Obstetrics
• Perinatology

Background:

• External cephalic version (ECV) is performed to convert breech presentations to cephalic.
• Previous studies suggest a potential link between early ECV (before 37 weeks) and increased late preterm birth.
• The specific factors contributing to this risk remain unclear.

Purpose of the Study:

• To investigate the association between performing ECV before term and the occurrence of late preterm birth.
• To identify potential risk factors that may moderate this association.

Main Methods:

• Secondary analysis of data from the international, multicenter Early ECV trials.
• Evaluation of the relationship between ECV exposure and late preterm birth (34 to 36 weeks gestation).
• Generalized linear mixed models were used to analyze data, accounting for center effects and adjusting for covariates.

Main Results:

• Among 1765 women with breech pregnancies, 749 (42.4%) underwent ECV before term.
• ECV before term was not independently associated with preterm birth.
• Anterior placenta location significantly moderated the association: women with an anterior placenta undergoing ECV before term had doubled odds of preterm birth (OR 2.05).

Conclusions:

• Women without prior preterm birth risk factors who have an anterior placenta and undergo ECV before term represent a subgroup at increased risk for late preterm birth.
• Placental location is a critical factor to consider when assessing the risks of early ECV.
• These findings suggest a need for individualized risk assessment in ECV procedures.