Prostaglandins, chorioamnionitis and preterm labour.

The production of prostaglandin E (PGE) and leukotriene B4 (LTB4) by amnion was measured in vitro in 12 women delivered after spontaneous preterm labour and in 15 women delivered after spontaneous labour at term. The placenta and fetal membranes were examined histologically in all cases. PGE output (fmol/mg dry weight/2 h) in the amnions from uncomplicated preterm deliveries was low (median 486, range 232-3203, n = 7) compared with the values obtained after spontaneous labour at term (5529, 1722-14,226, n = 15). In amnions from preterm deliveries complicated by acute chorioamnionitis or round cell infiltration there was massive release of PGE (15,262, 10,905-27,640, n = 5) which was accompanied by an increase in LTB4 production. Inflammatory infiltration of the fetal membranes results in a huge increase in PG production which could cause preterm labour.