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Maternal BMI influences risk for post-term delivery
The risk for post-term delivery — particularly delivery at 42 weeks’ gestation or later — increases with increasing maternal BMI, according to finding from a meta-analysis published in Obesity Reviews.
Nicola Heslehurst, PhD, of the Institute of Health and Society at Newcastle University in the United Kingdom, and colleagues conducted a systematic review and meta-analysis of 39 observational studies published in England since 1990 for a total population of 4,143,700 births. Researchers sought to determine the relationship between maternal BMI and post-term birth at 42 or more weeks’ gestation and at 41 or more weeks’ gestation.
Overall, 19 studies included data on post-term births at 42 or more weeks’ gestation and revealed a nonlinear association with statistically significantly increased odds for women with obesity class I (OR = 1.42; 95% CI, 1.27-1.58), class II (OR = 1.55; 95% CI, 1.37-1.75), class IIIa (OR = 1.65; 95% CI, 1.44-1.87) and class IIIb (OR = 1.75; 95% CI, 1.5-2.04); odds of delivery at 42 weeks’ or later gestation were decreased for women with underweight (OR = 0.81; 95% CI, 0.74-0.88).
Eleven studies included data on post-term births at 41 or more weeks’ gestation and revealed a nonlinear association with statistically significantly decreased odds for women with underweight (OR = 0.88; 95% CI, 0.83-0.95) and increased odds for those with obesity class I (OR = 1.26; 95% CI, 1.18-1.34), class II (OR = 1.39; 95% CI, 1.31-1.47) and class III (OR = 1.52; 95% CI, 1.44-1.54).
“The association between maternal BMI and post-term birth increases with increasing BMI, with the greatest odds among women in obesity class III and with post-term birth 42 weeks,” the researchers wrote. “Pregnancies which progress beyond 42 weeks have significantly increased risk of adverse outcomes, including perinatal morality. This presents a double burden of disease among women with morbid obesity, which is also associated with the highest levels of socioeconomic disadvantage compared with other BMI categories. Future maternal obesity research should consider the heterogeneity between obesity classes. Health care policy and practice should ensure that necessary interventions are in place to prevent the adverse outcomes associated with post-term birth, considering the increased risk among the higher obesity classes.” – by Amber Cox
Disclosure: The researchers report no relevant financial disclosures.