Determinants and consequences of major insulin-like growth factor components among full-term healthy neonates.

The purpose of this research was to investigate determinants of the insulin-like growth factor (IGF) system among healthy full-term newborns and explore their relation with anthropometric variables at birth. Components of the IGF system have been implicated in the pathogenesis of several forms of cancer, and perinatal events have been linked to chronic diseases in later life. Measurements of weight and length, as well as blood samples, were obtained from 331 healthy full-term newborns delivered during 1999 in Athens, Greece. Because the liver is important for IGF production, newborns were chosen to have bilirubin levels either < or = 8 mg/dl or > or = 12 mg/dl to operationally distinguish them according to the liver function. IGF-I, IGF-II, and IGF binding protein-3 were inversely associated with the presence of neonatal jaundice and blood creatinine, after controlling for blood protein levels. IGF-I increased rapidly and significantly over a period of a few days and was strongly positively associated with both birth weight and ponderal index. Newborn levels of IGF-I declined with maternal age. In comparison with first-born newborns, later-born ones had significantly higher blood IGF-I levels. We conclude that IGF-I plays a dominant role in growth during the perinatal period and that all three studied components of the IGF system are sensitive to liver and kidney function. These findings provide an insight into the processes involved in perinatal growth.