Large-for-gestational-age infants of type 1 diabetic mothers: An effect of preprandial hyperglycemia?

Objective. To determine how the frequency, timing and magnitude of hyperglycemia are associated with large-for-gestational-age (LGA) infants in pregnancies complicated by type 1 diabetes. Methods. Charts from pregnant women with type 1 diabetes (n = 70) were reviewed. Indices of maternal glycemic control were determined for seven gestational periods (weeks 7–10, 11–15, 16–19, 20–24, 25–28, 29–32 and 33–38) and compared between women who delivered LGA infants and appropriate-for-gestational-age (AGA) infants. Results. Of the 70 pregnancies, 57% of the infants were LGA (4.3 ± 0.4 kg) and 43% were AGA (3.2 ± 0.4 kg). Total maternal weight gain and rate of weight gain were significantly higher in mothers with LGA infants. The glycemic variables associated with an LGA infant were percentage of preprandial values above target for weeks 11–15, 25–28 and 29–32, and percentage of all values above target for weeks 33–38. For the entire pregnancy, the strongest predictors of an LGA infant were percentage of preprandial blood glucose values above target during weeks 29–32 and maternal weight gain. Conclusions. In pregnant women with type 1 diabetes, frequent episodes of preprandial hyperglycemia in the third trimester significantly impact the development of LGA infants.