USE OF FETAL ULTRASOUND TO SELECT METABOLIC THERAPY FOR PREGNANCIES COMPLICATED BY MILD GESTATIONAL DIABETES

OBJECTIVE - To determine whether fetal ultrasound early in the third t rimester can identify Latina with mild gestational diabetes mellitus ( GDM) whose fetuses are at risk for macrosomia and, if so, whether mate rnal insulin therapy can reduce that risk. RESEARCH DESIGN AND METHODS - Study subjects included 303 consecutive women with GDM and a fastin g serum glucose level < 5.8 mM on diet therapy who had a fetal ultraso und between 29 and 33 weeks gestation. Of the women, 98 (32%) had a fe tal AC greater-than-or-equal-to 75th percentile for gestational age, a nd 59 women completed a randomized trial of diet therapy (n = 29) or d iet plus twice daily insulin (n = 30). Maternal nutrient levels were a ssessed by meal tolerance testing (MTT) before and during therapy and by capillary glucose monitoring four to seven times a day. Birth weigh ts corrected for gestational age and neonatal glycemia and skin folds were the primary outcome variables compared between treatment groups. RESULTS - Diet and diet-plus-insulin groups were well matched for mate rnal age, prepregnancy relative weight, weight gain during pregnancy, and glycemia at entry. Insulin therapy reduced maternal capillary (P < 0.005) and MTT (P < 0.001) glucose levels and prevented a diet-associ ated rise in MTT triglyceride levels (P < 0.002). Gestational age at d elivery was similar in insulin- and diet-treated groups (39.6 +/- 0.2 vs. 39.5 +/- 0.2 weeks). Birth weights (3,647 +/- 67 vs. 3,878 +/- 84 g; P < 0.02), the prevalence of large-for-gestational age infants (13 vs. 45%, P < 0.02), and neonatal skin-fold measurements at three sites (P < 0.005) were reduced in the insulin-treated group. Rates of trans ient neonatal hypoglycemia were low in both treatment groups (14 and 1 8%, respectively) and did not differ significantly between groups. CON CLUSIONS - Fetal ultrasound early in the third trimester identified wo men with mild GDM whose infants were at high risk for fetal macrosomia in the absence of standard glycemic criteria for insulin therapy. Ins ulin treatment reduced the macrosomia, indicating that fetal ultrasoun d can be used to guide metabolic therapy in pregnancies complicated by mild GDM.