15-KETO-13,14-DIHYDROPROSTAGLANDIN-F2-ALPHA AND PROLACTIN IN MATERNAL AND CORD BLOOD DURING PROSTAGLANDIN-E2 OR OXYTOCIN THERAPY FOR LABOR INDUCTION

15-Keto-13,14-dihydroprostaglandin F2.alpha. plasma levels were measured in pregnant women following labor induction with either oral PGE2 treatment or intravenous oxytocin, both combined with amniotomy. The median time to start of contractions was 62 minutes in the PGE2 treated group and 45 minutes in the oxytocin treated group (p < 0.01; median test). The increase in 15-ketodihydro-PGF2.alpha. appeared earlier in the PGE2 group but not in the oxytocin group (p < 0.001 and p = 0.210, respectively). At delivery, the 15-ketodihydro-PGF2.alpha. values had further increased in both treatment groups. The increase was significantly higher in the PGE2 treated patients compared with oxytocin treated partients (p = 0.03; contrast test). Despite higher 15-ketodihydro-PGF2.alpha. concentrations throughout parturition, PGE2 women did not deliver more rapidly than oxytocin infused women. There was no correlation between 15-ketodihydro-PGF2.alpha. blood concentrations and either onset of contractions or labor time. The decrease in maternal serum prolactin concentration during parturition was pronounced (p < 0.001) in the PGE2 group but occurred also in oxytocin treated patients (p < 0.02). A single oral dose (0.5 mg) of PGE2 taken by non-pregnant women led to significant (p < 0.05) increases in 15-ketodihydro-PGF2.alpha. levels in blood plasma after 10 minutes. This increase persisted for at least 90 minutes. It is suggested that oral PGE2 may be transformed into PGF2.alpha. and/or induce endogenous PGF2.alpha. biosynthesis.