Maternal hormone profile in oxytocin induced labour.

Serial blood samples were collected from ten patients at between 40 and 42 weeks gestation, who were having labour induced by amniotomy and intravenous oxytocin. The plasma levels of human placental lactogen and pregnancy-specific beta 1 glycoprotein showed no more than their normal late pregnancy variability during labour; oestradiol-17 beta showed a small rise in early labour followed by a fall in the second stage of labour; unconjugated oestriol and 11-hydroxycorticosteroids showed a progressive rise throughout labour and progesterone a progressive fall. The ratio of progesterone to oestradiol-17 beta fell throughout labour. The significance of these changes in our understanding of the control of placental hormone secretion and of the hormone profile of spontaneous labour is discussed.