CHICAGO — Virtually any weight gain during pregnancy by obese women with gestational diabetes resulted in high rates of large-for-gestational-age infants, according to a study released at the annual meeting of the American College of Obstetricians and Gynecologists.
Obese women in the investigation who either lost weight or maintained their prepregnancy weight during pregnancy while on a medically supervised low-carbohydrate diet gave birth to babies with “close to normal” birth weights.
They also had the lowest cesarean delivery rates (10.5%), according to study results.
In contrast, more than one in five obese women who gained a modest amount of weight during pregnancy—1–14 pounds—had large-for-gestational-age infants.
The LGA rate increased with more weight gain, accounting for 36% of infants born to women who gained 26–35 pounds, and nearly 40% of those born to women who gained more than 35 pounds.
“We think this raises questions about current Institute of Medicine recommendations for obese women to gain a minimum of 15 pounds” during pregnancy, said Dr. Deborah L. Conway of the University of Texas Health Science Center at San Antonio.
Dr. Conway explained that her institution carefully monitors women with gestational diabetes and places them on a calorie-controlled, low-carbohydrate diet that includes nutritional counseling.
They also receive glyburide or insulin as necessary to achieve euglycemia.
“Although it wasn't the intention, we noticed that some of these women didn't gain weight as you might expect during pregnancy. We weren't sure that was such a bad thing,” said Dr. Conway during an interview at the meeting, where her study was presented in poster form.
To better understand gestational weight changes in this group, Dr. Poornima Kaul, a fourth-year resident, analyzed birth weights and pregnancy complications among 302 women with gestational diabetes who had a mean prepregnancy body mass index of 35.6 kg/m2 and were eligible for vaginal delivery.
The large-for-gestational-age rate among those who lost weight or maintained their prepregnancy weight was 11.8%. The macrosomia rate (weight greater than 4,000 g) among their infants was 8.8%, and the rate of small-for-gestational-age infants was 8.8%.
These rates are “pretty close to normal,” Dr. Conway said.
Infants born to women who gained a small amount of weight (1–14 pounds) had a 27.3% large-for-gestational-age rate and a 13.6% rate of macrosomia. These women had a 15.1% cesarean delivery rate.
Women who gained 15–25 pounds had rates of large-for-gestational-age, macrosomia, and cesarean delivery of 27.6%, 13.2%, and 23.4%, respectively.
Those who gained 26–35 pounds had rates of large-for-gestational-age, macrosomia, and cesarean delivery of 36.4%, 21.8%, and 26.7%, while rates in women who gained more than 35 pounds were 39.6%, 25%, and 17.2%.
Results from the study suggest that the current IOM guideline for a minimum 15-pound gestational weight gain “appears to reflect the upper limit of acceptable weight gain,” the study authors concluded.
Dr. Conway noted that new gestational weight guidelines are expected soon from the IOM and may reflect trends seen in their study.
Dr. Kaul and Dr. Conway reported no financial disclosures relevant to their study.