Objective: The purpose of this study was to explore the relation between birth weight variations that may occur in normal pregnancies and each of IGF-1 and C-peptide (reflecting insulin production).

Study Design: Maternal and cord serum samples were collected at delivery time of 30 selected women who had a singleton, full term uneventful pregnancy. Selected women included 10 who delivered large for gestational age neonates (LGA), 10 who delivered small for gestational age neonates (SGA) and 10 who delivered appropriate for gestational age neonates (AGA). Collected sera were analyzed for IGF-1 and C-peptide by radioimmunoassay.

Results : Mean maternal serum IGF-1 concentrations were higher in LGA than SGA group (P < 0.05) and mean cord serum IGF-1 levels were higher in LGA neonates than both AGA (P < 0.05) and SGA (P < 0.01) neonates. There was no correlation between maternal serum values of IGF-1 and birth weights and between maternal and fetal serum IGF-1 levels in all groups. Fetal IGF-1 serum levels were significantly correlated to birth weight of LGA (r = 0.8468, P < 0.01) and AGA (v = 0.8717, P < 0.01) neonates. Mean maternal serum C-peptide levels were higher in LGA than AGA (P < 0.01) and SGA (P < 0.001) groups. Mean cord serum C-peptide values were higher in LGA than SGA neonates (P