Heterogeneity of fetal growth in type 1 diabetic pregnancy

Objective: To investigate the frequency of macrosomia in an homogeneous coh ort of type 1 diabetic mothers and to analyze the influence of maternal fac tors and glycemic control on the incidence of fetal macrosomia. Material and methods: Fifty-five consecutive type 1 diabetic first pregnanc ies were prospectively studied. Macrosomia was defined by a ponderal index above the 90(th) percentile. Venous cord blood levels of insulin, C peptide and leptin were measured at delivery. The influence of HbA1c levels and ot her maternal variables on the occurrence of macrosomia and on the ponderal index was assessed using a stepwise regression logistic model. Results: The mean (+/- SD) birth weight was 3482 (+/- 497) g at 37.4 +/- 1. 0 weeks gestation. Ma crosomia occurred in 29 cases (53.7%). Feta I insulin , C peptide and leptin levels were significantly higher in macrosomic than in non macrosomic infants. Maternal age, duration of diabetes, pregravid bo dy mass index, parity, weight gain during pregnancy, presence of a microang iopathy, nephropathy, smoking habits, gestational hypertension or preeclamp sia, and HbA1c levels throughout pregnancy did not differed between mothers of macrosomic and non macrosomic infants. In the stepwise analysis none of these covariates was explanatory of the ponderal index. Conclusions: The frequency of macrosomia remains very high in infants of ty pe 1 diabetic mothers despite a reasonable degree of glycemic control. The variability of the fetal growth response to mild hyperglycemia prompts for the identification of other factors involved in the modulation of fetal gro wth.