[Does fetal oxytocin initiate human labour? A hypothesis]

The concentration of specific oxytocin receptors increases during pregnancy and reaches a maximum at term after the onset of spontaneous labour. This constitutes a biochemical explanation for the well-known increase of oxytocin sensitivity during pregnancy. Oxytocin receptors were also found in human decidua and their concentration increased similarly. Based on these results the hypothesis was set up that oxytocin leads to an increase in prostaglandin production though specific receptors in decidua. Under specific incubation circumstances oxytocin indeed increased prostaglandin E and prostaglandin F synthesis of decidual tissue. In induction of labour with oxytocin PGF-levels in the maternal peripheral plasma increased significantly in all women in whom induction was successful. Since it is known that the fetus secretes considerable amounts of oxytocin in case of labour of spontaneous onset the hypothesis was set up that fetal oxytocin may initiate human labour by the mechanisms described above.