Weight gain by 24 weeks may predict GDM risk

Gestational weight gain within the first 24 weeks is a significant prognostic factor for gestational diabetes mellitus (GDM), particularly in women who already were overweight or obese before becoming pregnant, according to a retrospective cohort study.

The study examined the charts of 652 women, 163 who had developed GDM and 489 nondiabetic controls matched 3 to 1 by prepregnancy body mass index (BMI), age, race, and parity. Weight gain at 12 weeks' gestation for women in the GDM group was almost twice that of controls (4.0±8.2 lbs vs 2.8±6.5 lbs) and by 24 weeks, the GDM cohort had gained significantly more weight than controls (14.8±12.7 lbs vs 11.2±10.8 lbs; P<.001). Regardless of prepregnancy BMI, mean weight gain in the GDM group at 24 weeks was higher than that of controls.

Total weight gain during pregnancy differed significantly between controls and women with GDM who were overweight (P=.004) or obese (P=.008) before pregnancy. However, no significant difference in weight gain was seen between the GDM and control groups in women who were underweight or at normal weight before pregnancy.

The authors propose that because overweight and obese women have increased insulin resistance before conception, "the increase in gestational weight gain by 24 weeks may 'push them over the edge' toward GDM development."

As to the relationship between severity of GDM and 24-week weight gain, women whose diabetes was controlled with diet and exercise and those using insulin showed no difference in the 1-hour glucose challenge.

Gibson K, Waters TP, Catalano PM. Maternal weight gain in women who develop gestational diabetes mellitus. Obstet Gynecol. 2012;119(3):560-565.