Serum levels of IGF-I and IGF-binding protein (IGFBP-1) have been determined in the maternal circulation between 11 and 42 weeks of gestation in women not in labour (n=335) and in the maternal and fetal circulations at the time of delivery between 37 and 42 weeks (n=55). Maternal serum (MS) IGF-I levels increased during pregnancy and showed a significant positive correlation with maternal weight (P=0·0033) but no correlation with birthweight. The MS IGFBP-1 levels did not change during the second and third trimesters and showed a negative correlation with birthweight, maternal weight, placental weight and MS glucose (P=0·0002, P<0·0001, P=0·047, P=0·024 respectively). MS IGFBP-1 levels were higher in small-for-gestational age babies than in average-for-gestational weight babies (P=0·026) and lower in the large-for-gestational weight group (P=0·048). There was a significant rise in mean MS IGFBP-1 levels during labour (P=0·0005). These findings suggest that IGFBP-1 may be an important factor in pathological growth retardation.
Journal of Endocrinology (1996) 148, 303–309