The prevalence of maternal obesity is rising, the authors explain, and pregestational obesity is a recognized risk factor for diabetes, preeclampsia and hypertension, macrosomia, and cesarean delivery. Whether obesity and diabetes contribute independently to the risk of cesarean delivery had been unclear.

Dr. Hugh M. Ehrenberg and colleagues from Case Western Reserve University School of Medicine, Cleveland, Ohio examined the independent influence of pregravid obesity and diabetes on the occurrence of primary cesarean delivery in 12,303 women for whom complete records were available.

Compared with women having a normal body-mass index (BMI), obese women faced a much higher risk of cesarean delivery (13.8% versus 7.7% in normal women), the authors report. Cesarean delivery rates were also significantly higher in overweight women (10.4%).

The rates of cesarean delivery were also higher in women with gestational diabetes treated with diet alone (16.7%) and in women with insulin-treated pregestational diabetes (24.7%), the report indicates.

In multiple regression models, increasing BMI and pregestational diabetes conferred independent risks for cesarean delivery, the researchers note, whereas gestational diabetes did not significantly alter cesarean delivery risk after controlling for confounding variables.

The risk of cesarean delivery rose with increasing BMI, the investigators report, whereas the elevated risk of cesarean delivery associated with pregestational diabetes remained relatively constant as BMI increased.

"With the relative prevalence of obesity and diabetes in our population and the rising rate of obesity among gravida women, obesity exerts a more significant influence on the risk of cesarean delivery overall," the authors write.

"Our findings have important implications for preconceptional counseling of overweight and obese women, the researchers conclude.

Source: Diabetes In Control.com: Am J Obstet Gynecol 2004;191:969-974.