Umbilical artery concentrations of androstenedione increase in early labour in the leading twin fetus

Abstract

Umbilical artery concentrations of androstenedione, progesterone, pregnenolone, pregnenolone sulphate and dehydroepiandrosterone sulphate were measured at birth in twin pairs, born by caesarean section. In the group born before the onset of labour, there were no significant differences in concentration of any of the steroids between the leading twin (twin I) and the second twin (twin II). In the group born during the latent phase of labour, levels of umbilical artery progesterone were significantly less in twin I (mean 501, SE 112 nmol/l) than in twin II (mean 887, SE 131) (P less than 0.05), while concentrations of androstenedione were increased in twin I [9.9 (SE 1.7) vs 4.7 (SE 0.7) nmol/l, P less than 0.01]. In patients delivered during active labour, androstenedione levels were consistently increased in twin I compared with twin II [11.7 (SE3.4) vs 4.3 (SE 0.7) nmol/l, P less than 0.01]. It is suggested that the rise in umbilical artery levels of androstenedione is derived from the fetal adrenal gland and may have an important role in the onset of labour.