External cephalic version: Predictors of success and influence on caesarean rates

Success rate of external cephalic version in relation to the woman's body mass index and other factors-a population-based cohort study

INTRODUCTION

The aim of this study was to evaluate the impact of women's body mass index (BMI) on the probability of a successful external cephalic version (ECV).

MATERIAL AND METHODS

A retrospective population-based observational study including all women that underwent an ECV in the southeast region of Sweden from January 2014 to December 2019. Data were collected from electronic medical records, Obstetrix, Cerner. The women were divided into BMI categories according to the World Health Organization classification. Women with a BMI below 25 kg/m² formed the reference group. Crude and adjusted odds ratios for unsuccessful ECV in each BMI group were calculated using binary logistic regression. Furthermore, the association between maternal characteristics and clinical and ultrasound variables at the time of the ECV and unsuccessful ECV was evaluated.

RESULTS

A total of 2331 women were included. The overall success rate of ECV was 53.4%. Women with a BMI below 25 kg/m² had a success rate of 51.3% whereas obese women had a success rate of 58.6%. The risk of an unsuccessful ECV among obese women (BMI ≥30 kg/m² ) had an OR of 0.74 (95% CI 0.59-0.94) compared with women with a BMI below 25 kg/m² . After adjusting for suitable confounding factors, the association was no longer significant. Higher maternal age, multiparity, higher gestational age, posterior placenta position, polyhydramnios and higher estimated weight of the fetus at the ECV significantly decreased the risk of an unsuccessful ECV.

CONCLUSIONS

Maternal obesity does not seem to negatively influence the success rate of ECV. This is a finding that may encourage both caregivers and obese pregnant women to consider an ECV and so avoid a planned cesarean section for breech presentation in this group.

External cephalic version: Predictors for success

OBJECTIVES

The objective of this study was to identify the factors predictive of the success of external cephalic version (ECV).

METHODS

A single-centre retrospective observational study was performed in the maternity ward of the Angers University Hospital, France, between January 2010 and May 2020. The study included all patients (n = 613) for whom an ECV was performed for a breech or transverse foetus. The primary endpoint was measured by the success of the ECV, defined by the visualisation, using pelvic ultrasound, of the foetus in cephalic presentation immediately after the manoeuvre. Following to the ECV, the cohort was separated into two groups; ECV Success and ECV Failure. In order to determine the predictive factors of success, a logistic regression model was performed, including the parameters of: parity, foetal presentation during ECV, the side of the foetal back, placental location, type of operator and maternal age. The results are presented as (odds ratio [confidence intervals]; p-value). The significance threshold was defined by a p-value < 0.05.

RESULTS

The ECV success rate was 21.4% (131/613). The factors predictive of the success of ECV were: transverse foetal presentation (2.7 [1.3-5.6]; p<0.01); a senior physician operator (1.6 [1.2-2]; p<0.01); multiparity (1.6 [1.2-2]; p<0.01); non anterior placental localization (1.4 [1.1-2]; p<0.01). A number of attempts greater than 3 were significantly associated with reduced chances of success (0.3 [0.2-0.4]; p<0.01).

CONCLUSION

The study shows that transverse foetal presentation, a senior physician operator, multiparity, as well as a non-anterior placental location are factors predictive of the success of ECV. Knowledge of these factors can improve the information given to patients.