Pregnancy weight gain for obese women: What is safe?

There’s no consensus on how much weight an overweight or obese woman should gain during pregnancy--in 2009 the Institute of Medicine changed its guidelines, lowering it to 11 to 20 pounds for obese moms-to-be, but not everyone agrees. A study finds that there may be few differences in pregnancy-related results for women who gain more or less weight.

The study, published in the December issue of the journal Obesity, looked at data on 691 obese women. Of those, 57.7% had a pre-pregnancy body mass index of 30 to 34.9 (considered level I obesity), 27.1% had a BMI of 35 to 39.9 (level II obesity) and 15.2% had a BMI of 40 or greater.

Among those women, about half gained a more traditional amount of weight during pregnancy, 25 to 35 pounds, and the others gained 11 to 20 pounds, considered the new range as suggested by the Institute of Medicine.

Average infant birth weight was about the same in both groups and no differences were seen in numbers of low birthweight infants or admissions to neonatal intensive care units.

Women who gained weight in the new range had slightly fewer cesarean deliveries compared with those who gained more: 39.3% versus 44.3%. There was also a minor difference between the groups in how many women developed pregnancy-related high blood pressure: 11.5% in the new range group and 15% in the traditional group.

Although the study didn’t examine health effects in the long-term, the authors wrote that their results suggest that obese pregnant women may be able to safely gain the amount of weight recommended by the Institute of Medicine.