CIRCULATING LEVELS OF IGF-I AND IGF-BINDING PROTEIN-1 THROUGHOUT PREGNANCY - RELATION TO BIRTH-WEIGHT AND MATERNAL WEIGHT

Serum levels of IGF-I and IGF-binding protein (IGFBP-1) have been dete rmined in the maternal circulation between 11 and 42 weeks of gestatio n in women not in labour (n = 335) and in the maternal and fetal circu lations at the time of delivery between 37 and 42 weeks (n = 55). Mate rnal serum (MS) IGF-I levels increased during pregnancy and showed a s ignificant 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 correlati on 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 avera ge-for-gestational weight babies (P = 0.026) and lower in the large-fo r-gestational weight group (P = 0.048). There was a significant rise i n mean MS IGFBP-1 levels during labour (P = 0.0005). These findings su ggest that IGFBP-1 may be an important factor in pathological growth r etardation.