INSULIN-LIKE GROWTH-FACTORS (IGFS) AND IGF-BINDING PROTEINS (IGFBP-1,IGFBP-2 AND IGFBP-3) IN DIABETIC PREGNANCY - RELATIONSHIP TO MACROSOMIA

To evaluate the role of insulin-like growth factors (IGFs) and IGF-bin ding proteins (IGFBPs) in exessive fetal growth (macrosomia) in diabet ic pregnancy, 84 insulin-treated diabetic mothers and their infants we re tested for serum concentrations of IGF-I, IFG-II, and IGFBP-1, -2 a nd -3. These parameters were correlated with the birth weight of neona tes and placental weight. IGF-I and II levels were determined by speci fic radioimmunoassays (RIAs) after serum samples were extracted with a id-ethanol. IGFBPs were measured by Western immunoblot with specific a ntibodies to the respective IGFBP species. Serum concentrations of bot h IGF-I and IGF-II in mothers with either IDDM or NIDDM increased with the gestational period, reached a plateau at the third trimester, and returned to non-pregnant levels within 7 days after delivery. These v alues were not different from those in normal mothers before and throu ghout pregnancy. As previously reported, IGF-I concentrations in cord serum of neonates born to diabetic mothers were (P<0.01) higher than t hose of newborns of normal mothers. Likewise, cord blood IGF-II levels were 2-fold higher in babies of diabetic mothers (P<0.001). Fetal IGF -I and IGF-II correlated with each other and with maternal HbA1c, and they positively correlated with either birth weight or placental weigh t. Cord IGFBP-3 concentrations were significantly higher in diabetic p regnancy, but IGFBP-2 concentrations were not different from those in normal pregnancy. Cord IGFBP-1 concentrations were significantly highe r only in babies of mothers with IDDM. None of these cord IGFBP concen trations correlated with birth weight or placental weight. The data su ggest that fetal IGF-II, like IGF-I, is involved in fetal and placenta l growth in diabetic pregnancy. The role of IGFBPs remained to be dete rmined.