Developmental regulation of circulating insulin-like growth factor-binding proteins in normal pregnancies and in pre-eclampsia

The insulin-like growth factors (IGFs) and their binding properties (IGFBPs) are believed to play important roles in the growth and development of the human fetus. They have been implicated in the pathophysiology of pre-eclampsia. In this study we have characterized the developmental regulation, in normal and pre-eclamptic pregnancies, of IGFs and IGFBPs in maternal serum, neonatal serum and amniotic fluid. In neonatal cord serum IGFBP-1, -2 and -6 decreased with increasing gestational age. In contrast, the ternary complex and its components, IGF-I, IGFBP-3 and ALS increased with gestation. We show that while ALS is an important limiting factor for ternary complex formation in the fetal circulation, there is a fraction of IGFBP-3 which is unable to form this complex. IGFs and IGFBPs in the maternal and fetal circulation were similar in normal and pre-eclamptic pregnancies.