Maternal obesity is considered an impediment for a successful external cephalic version (ECV). We aimed to evaluate the impact of maternal pre-pregnancy body mass index (BMI) and weight gain during pregnancy (WG) on the success rate of ECV. Retrospective analysis of the United States (US) Natality Live Birth database from the Centers for Disease Control and Prevention (2016-2018). The data were analyzed for singleton term births following an ECV attempt with a birth weight between 2500 and 5000 grams. Women were divided into several groups based on their BMI and WG. The success rates of ECV were compared among the different BMI and WG categories using the Pearson chi-square test with the Bonferroni adjustment for multiple comparisons. A logistic regression was used to calculate the independent contribution of maternal BMI and WG to the success of ECV, after controlling for maternal race/ethnicity, parity and neonatal birth weight. Results were displayed as odds ratios with 95% confidence intervals, and statistical significance was determined as a p-value below 0.05. Of the 11,150,527 live births in 2016 to 2018, 26,255 women who underwent an ECV attempt met the inclusion criteria. The overall ECV success rate was 52.75% (13,850 women). The success rates of ECV for the different BMI and WG categories ranged from 47.43% to 55.18% (Table 1). Although the overall differences in the success rates were small, a logistic regression model demonstrates that the odds for a successful ECV consistently decline with increasing BMI and with increasing WG (Table 2). We document a significant association between increases in both maternal BMI and WG and lower success rates of ECV. Nevertheless, given the small magnitude of these differences, with the exception of Extreme Obesity, these statistically significant differences are not clinically significant. Clinicians should therefore not rely heavily on maternal weight when considering an ECV attempt.View Large Image Figure ViewerDownload Hi-res image Download (PPT)
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