Antenatal dexamethasone and the growth hormone-insulin-like growth factor axis

Dexamethasone administration has marked effects on the growth hormone-insul in-like growth factor axis (GH-IGF) in animal and human studies. During pre gnancy in the rat, it is associated with fetal growth restriction due to in hibition of IGF bioactivity, In the human only repeated dosages have been a ssociated with fetal growth restriction. The aim of this study is to test t he hypothesis that antenatal dexamethasone administration to pregnant women is associated with reduced activity of the GH-IGF axis. To achieve this bl ood samples were taken from 12 pregnant women pre- and at 24 h and 48 h aft er dexamethasone administration, In these samples GH, IGF-I, IGF bioactivit y and IGF binding protein (IGFBP)-3 protease activity were measured. In vie w of the interaction between insulin and the GH-IGF axis, glucose and insul in concentrations were also measured. There were no significant differences between the concentrations of GH, IGF-I, IGF bioactivity and IGFBP-3 prote ase activity before and after dexamethasone, The concentrations of glucose and insulin were significantly higher at 24 h, but not 48 h post-dexamethas one. It is concluded that a single antenatal course of dexamethasone does n ot alter the GH-IGF-I axis in pregnant women at the time points studied.