Fetal prostaglandin levels in twin pregnancies.

Umbilical venous plasma and amniotic fluid concentrations of prostaglandins E2 (PGE), F2 alpha (PGF) and 13,14 dihydro-15-keto-F2 alpha (PGFM) were measured in 31 twin pregnancies by specific radioimmunoassays. There was no significant difference between twins I and II in the same pregnancy but PGE and PGFM were significantly increased during labour in fetal blood. This rise was not manifest in the latent phase. PG concentration in amniotic fluid rose with advancing gestational age but was more pronounced in the case of PGE than for PGF and PGFM. No significant differences between amniotic sac concentrations of PGs of twin I and II were found during the prelabour period, but in all four patients in labour with intact membranes, the PG levels were increased in twin I. The fetal plasma and amniotic fluid levels of PGE and PGFM were significantly correlated in the prelabour group.