IGFBP-1 in the placenta, membranes and fetal circulation: levels at term and preterm delivery.

Samples of maternal blood, amniotic fluid, placenta, fetal membranes and umbilical venous blood were collected from 59 women at vaginal delivery (32-41 weeks gestation) and 15 women at delivery by Caesarean section (37-41 weeks gestation). Umbilical vein levels of IGFBP-1 were significantly lower in deliveries prior to the onset of labour (elective Caesarean section) than those during normal vaginal delivery. These levels were, in turn, significantly lower than those delivered by emergency Caesarean section. This difference was not seen in any of the other tissues examined. Concentrations of IGFBP-1 were lower in placenta and membrane extracts from preterm deliveries than in term deliveries. This difference was not observed in maternal or fetal serum or in amniotic fluid. This study confirms that the fetal membranes are a major source of IGFBP-1 and that fetal circulating levels are raised where there is evidence of fetal hypoxia. The absence of a comparable rise in levels in placenta, membranes or amniotic fluid suggests that the origin of this increase is from fetal tissue.