Relation between corticosteroid and albumin concentrations in umbilical vein plasma and the duration of labour.

The concentration of corticosteroids in the umbilical vein plasma of babies delivered after a spontaneous onset of labour showed a significant positive correlation with the duration of labour (r=0-593; P less than 0-001) and the length of the second stage (r=0-48; P less than 0-02). Similar results were also obtained for induced labours. For labours of both induced and spontaneous onset, the albumin concentration in cord plasma also correlated significantly (r=0-46; P less than 0-01) with the corticosteroid concentration. It is concluded that the stress of labour and vaginal delivery, and possibly changes in the concentration of proteins which bind corticosteroids, are impoertant in determining the corticosteroid concentration in cord plasma obtained after delivery of the baby. The significance of these findings in relation to mechanisms responsible for the onset of human labour is discussed.