Prostaglandins E and F in amniotic fluid during stretch-induced cervical softening and labor at term.

An unspecified region of the uterus of 7 healthy pregnant patients at term, not yet in labor, was mechanically distended by extraamniotic application of rubber bougies. In all cases, significant onset of labor was noted within 20 min to 5 h, cervical softening progressed with time, and delivery was achieved within 21 h. Significant elevation of prostaglandin E (PGE) and F (PGF) levels in amniotic fluid was noted with the progress of cervical dilatation. It appears that the release of PGE and PGF is dependent on uterine stretching and/or the subsequently induced uterine contractions. A possible source of the release of PG in the present study was discussed.