Newly published research is challenging guidelines from the American College of Obstetricians and Gynecologists stating that all women, even those who are obese, should gain between 26 to 35 pounds during their pregnancy.

The Institute of Medicine has recommended a lower amount of weight gain for overweight and obese patients, about 15 pounds, but the new data suggest that even this is too much and goes on to show that these patients can safely be placed on a calorie-appropriate nutritional program.

“Women who are obese when beginning a pregnancy are, by definition, unhealthy,” lead author Dr. Yvonne S. Thornton, from New York Medical College, Valhalla, said in a statement. “To say that they should gain even more weight is counter-intuitive, and our study bears that out.”

The study, reported in the Journal of the National Medical Association, featured 232 obese pregnant women who were assigned to follow conventional “eat to appetite” prenatal nutritional guidelines or to participate in a well-balanced, monitored nutritional program involving the use of daily food diaries.

On average, women in the study group gained 11 pounds, while comparison subjects gained 31 pounds. Twenty-three subjects with extreme obesity lost weight during their pregnancy.

Contrary to what some prior researchers may have feared, use of the nutritionally monitored program did not result in any fetal deaths or any growth-restricted infants.

Moreover, women who adhered to the nutritional regimen had fewer babies weighing over 10 pounds, fewer cesarean sections, a lower rate of gestational diabetes, and less weight after delivery.

“Rather than focusing on numerical endpoints with respect to weight gain, we need to focus on making (obese) women healthier by getting them to eat a well-balanced diet,” Thornton emphasized.

SOURCE: Journal of the National Medical Association, June 2009.