Concentration of 13,14-dihydro-15-keto-prostaglandin E2 in the maternal peripheral plasma during labour of spontaneous onset

Summary. The concentration of 13, 14-dihydro-15-keto-PGE₂ (PGEM) was measured by radioimmunoassay in pregnant women in the third trimester, in women at term but not in labour and during labour of spontaneous onset. The plasma concentration of PGEM in pregnant women was elevated above that in a non-pregnant control group. Before the onset of labour no increase of PGEM concentration could be identified. Women in labour had higher PGEM plasma concentrations than before the onset of labour, although there was no progressive increase. Immediately after delivery PGEM levels reached a maximum, which decreased significantly to pre-labour values within 30 min. Artificial rupture of the membranes had no influence on plasma PGEM levels. It is concluded that labour is associated with an increased synthesis of PGE₂ and that PGE₂ may be inved in the mechanism of placental separation. The rapid disaearance of high PGEM levels after labour confirms that PGE₂ is probably synthesized mainly in the fetal compartment.