[The relation between human fetal growth and the blood levels of insulin-like growth factor-I]

To determine the relation between human fetal growth and the levels of insulin growth factor-I (IGF-I) in both the maternal and fetal compartments.

Serum samples were obtained from pregnant woman(n = 171) and their neonate cord blood(n = 164) between 32-42 weeks of gestation. The woman and the neonate were divided into three groups by the birth weight of newborn. In large for gestational age (LGA) group, the 77 cases were from pregnant woman and the 64 cases were from their neonate; in average for gestational age (AGA) group, the 59 cases were from pregnant woman, the 59 cases were from their neonate; and in small for gestational age (SGA) group, the 35 cases were from pregnant woman and 43 cases were from their neonate. The serum samples were analyzed by radioimmunoassay for the levels of IGF-I.

The levels of IGF-I in the neonatal serum were lower than those in maternal blood (P < 0.01). The levels of IGF-I in SGA group were lower than those in the other groups (P < 0.05). There was significant correlation between gestational ages and the levels of IGF-I (r = 0.91-0.98), but not in SGA group (r = 0.21-0.81). There was a direct correlation between the levels of IGF-I in the cord blood and the neonatal weight (P < 0.05).

These data demonstrate that the level of expression and regulation of IGF-I in maternal and fetal compartments were independent of each other. The IGF-I level in cord blood is shown to be adjunctively and directly associated with fetal size in pregnancies and the IGF-I plays the precise role in deviant fetal growth.