FETAL AND MATERNAL PLASMA INSULIN-LIKE GROWTH-FACTORS AND BINDING-PROTEINS IN PREGNANCIES WITH APPROPRIATE OR RETARDED FETAL GROWTH

A prospective observational study of 104 women was performed to study whether the insulin-like growth factor (IGF) system in pregnancy befor e labour is associated with reduced fetal growth. Fetal blood was obta ined by cordocentesis for prenatal diagnosis or at elective caesarean delivery and a maternal sample was also obtained. IGF-1 and ICF-2 and their binding proteins -1 and -3 were measured by RIA. The 35 cases we re smaller than -2S.D.s by ultrasound abdominal circumference and birt hweight and were subdivided into fetal growth retardation (FGR, n = 20 ) and small for gestational age (SGA, n = 15) by Doppler velocimetry a nd neonatal outcome. Controls (n = 69) were normally grown. Control ma ternal IGF-1 (r = 0.65, P < 0.0001) and IGFBP-3 (r = 0.46, P = 0.001) increased with advancing gestational age. In FGR cases, maternal IGF-1 was low (P = 0.0001) and IGFBP-1 was high (P = 0.03) and maternal IGF -2 was low in SGA (P = 0.005). In the SGA fetus, IGF-2 was low (P = 0. 0009) and IGFBP-3 (P = 0.02) was high. In FGR, IGFBP-1 (P < 0.0001) an d IGFBP-3 (P = 0.002) were both elevated. These data do not support th e hypothesis that fetal IGF-1 deficiency is a common cause of FGR. Ele vated binding proteins may lead to a relative deficiency of free IGF b ut changes in binding proteins may be secondary to metabolic changes. In FGR, maternal IGF-1 was low with high binding proteins, so this sys tem may be important in controlling placental transfer. (C) 1997 Elsev ier Science Ireland Ltd.