Insulin-Like Growth Factors in Fetal Macrosomia with and without Maternal Diabetes

Abstract

Insulin-like growth factors (IGFs/somatomedins) have been implicated as regulators of fetal growth. This study investigates whether IGFs are related to macrosomia in infants of normal or insulin-dependent diabetic mothers. Cord concentrations of IGF-I (radioimmunoassay), total IGF (radioreceptor assay) and IGF binding protein (radiobinding assay) were measured in 15 term infants of diabetic mothers (IDM) and 29 term infants of nondiabetic mothers. In infants of control mothers cord IGF and total IGF levels were significantly higher in large-for-gestational-age than appropriate-for-gestational-age infants; but this relationship was lost in IDM, in whom IGF-I concentrations were similar to control infants. IGF binding protein levels were not significantly different in any of these groups. The absence of elevated IGF levels in macrosomic IDM indicates that the pathologic process does not involve a simple increase in these growth factors.