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 study 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%) in the study.
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 (LGA) 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, 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.
The Institute of Medicine is still recommending an 11- to 20 -lb weight gain for obese women during pregnancy in its recently released new guidelines. “What we saw in our study was that under nutritional supervision, it did not appear necessary for obese women with gestational diabetes to gain weight to have normal obstetrical rates of outcome and normal fetal size,” she said in a later interview.
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/m
The LGA 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% LGA 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 LGA, macrosomia, and cesarean delivery of 27.6%, 13.2%, and 23.4%, respectively.
Those who gained 26–35 pounds had rates of LGA, 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%.
Dr. Kaul and Dr. Conway reported no disclosures.
Dr. Deborah L. Conway (right) and Dr. Poornima Kaul found that more than one in five obese women who gained a modest amount of weight during pregnancy—1–14 pounds—had LGA infants. The LGA rate increased with more weight gain. COURTESY LESTER ROSEBROCK/UT HEALTH SCIENCE CENTER SAN ANTONIO