Insulin-like growth factor-I and its binding proteins in healthy mothers and their newborns

Abstract

Objective: To determine serum levels of insulin-like growth factor-I, free insulin-like growth factor-I and its binding proteins in maternalserum and in cord blood of two groups of newborns with differentbirth weights. Methods: A group of 60 healthy pregnant womenand their respective neonates with birth weight ≥ 2500g (group 1)and another comprising 23 healthy pregnant women and theirrespective neonates with birth weight ≤ 2500g (group 2) werestudied. Maternal and neonatal blood samples were analyzed forlevels of insulin-like growth factor-I, free insulin-like growth factor-I, binding protein-1 and binding protein-3 by radioimmunoassay.Statistical analysis: Student’s t test and multiple regressionanalysis. Values of p < 0.05 were considered statisticallysignificant. Results: The t test showed that maternal insulin-likegrowth factor-I, neonatal insulin-like growth factor-I, and neonatalbinding protein-3 values were significantly higher in Group 1 thanin Group 2. In both groups maternal values were higher than thoseof their neonates (p < 0.05). Multiple regression analysis showeda positive correlation between neonatal anthropometric variablesand neonatal insulin-like growth factor-I. Maternal binding protein-1 showed a negative correlation with neonatal insulin-like growthfactor-I and binding protein-3. There was a positive correlationbetween maternal insulin-like growth factor-I and neonatal ratiofree insulin-like growth factor-I/total insulin-like growth factor-I.Conclusion: The findings of this study suggest that insulin-likegrowth factor-I and its binding proteins 1 and 3 play a role in theregulation of late fetal growth in normal Brazilian pregnant women.

Keywords

• Somatomedins
• Carrier proteins
• Pregnant women
• Infant
• newborn
• Birth weight