In a woman with a normal weight pre-pregnancy body mass index (BMI), i.e. 18.5-24.9, the weight gained during pregnancy does not exceed a total weight gain of 25 lbs. In a woman with an underweight pre-pregnancy body mass index (BMI), i.e. less than 18.5, the weight gained during pregnancy does not exceed a total weight gain of 28 lbs. In a woman with an overweight pre-pregnancy body mass index (BMI), i.e. 25.0-29.9, the weight gained during pregnancy does not exceed a total weight gain of 15 lbs. In a woman with an obese pre-pregnancy body mass index (BMI), i.e. greater than 30, the weight gained during pregnancy does not exceed a total weight gain of 11 lbs. These standards are supported for the whole population irrespective of height, race or ethnicity. [from
NCI]