SMFM: Very Obese May Need to Gain Less Pregnancy Weight

February 26, 2011

Women who are extremelly obese may not need to gain as much weight during the second and third trimesters of pregnancy as current guidelnes recommend, according to research presented at the Society for Maternal-Fetal Medicine's annual meeting, The Pregnancy Meeting, held from Feb. 7 to 12 in San Francisco.

MONDAY, Feb. 14 (HealthDay News) -- Women who are extremely obese may not need to gain as much weight during the second and third trimesters of pregnancy as current guidelines recommend, according to research presented at the Society for Maternal-Fetal Medicine's annual meeting, The Pregnancy Meeting, held from Feb. 7 to 12 in San Francisco.

Eva Pressman, M.D., of the University of Rochester Medical Center in New York City, and colleagues evaluated 73,977 women who gave birth to a single child between January 2004 and December 2008. The investigators also assessed two oxytocin protocols (lower dose every 45 minutes and higher dose every 30 minutes) in nearly 500 women based on body mass index (BMI).

The investigators found that gaining less weight than recommended in the second and third trimesters was associated with increased likelihood of having a baby that was small for gestational age in all BMI groups except for obese class II and III. In addition, gaining more weight than recommended in the second and third trimesters was tied to an increased likelihood of having a baby that was large for gestational age in all BMI groups. The likelihood of cesarean delivery, induction of labor, and gestational diabetes increased for all BMI groups above normal weight. Compared to overweight and obese women administered a lower, less frequent dose of oxytocin, overweight and obese women administered a higher, more frequent dose were more likely to deliver vaginally.

"If you give more oxytocin to overweight and obese patients they may be more likely to delivery vaginally, which is what we want, as opposed to having a cesarean section, which can introduce more complications," Pressman said in a statement. "The study is important because the effect of BMI on induction has not been well described before."

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