Obesity that complicates pregnancy has increased significantly over the past 15 years, according to researchers from Case Western Reserve University School of Medicine in Cleveland, OH.

The researchers compared the prevalence of obesity in 31,542 pregnancies from January 1986 to December 1996 to the prevalence of obesity in 15,600 pregnancies between January 1997 and June 2001, with a weight of 200 pounds or more defined as obese.

"Maternal obesity was significantly more common" in the later group, the researchers reported in the American Journal of Obstetrics and Gynecology.

The researchers said that women with "milder obesity (201–250 pounds prepregnancy weight) were at increased risk for a high blood pressure condition known as preeclampsia, gestational and insulin-dependent diabetes mellitus, advanced gestational age (42 weeks), fetal macrosomia, and cesarean delivery."

Comparing obesity rates before and after 1997, the researchers found that the risk for maternal obesity had climbed 42 percent among African-American women, 29 percent among white women and 26 percent among Hispanic women -- but had decreased by 40 percent among Asian women.

"The risk of perinatal complications increases with increasing maternal pregravid weight; even those women with moderate obesity are at increased risk of adverse outcomes," the researchers concluded.

Other sources: American Journal of Obstetrics and Gynecology