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

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 involved in the mechanism of placental separation. The rapid disappearance of high PGEM levels after labour confirms that PGE2 is probably synthesized mainly in the fetal compartment.     

Effect of cervical application of prostaglandin (PG) E2 on plasma 13,14-dihydro-15-keto-PGF2α and oxytocin in pregnant women at term

Summary. The concentrations of 13,14-dihydro-15-keto-prostaglandin F_2α (PGFM) and oxytocin were measured by radioimmunoassay in the peripheral plasma of 21 women with low Bishop scores in whom cervical ripening and labour were induced with a cervical cap containing 1.5 mg of prostaglandin (PG) E₂, left in place for 6 h. Blood samples were taken before and at 3, 6, 9 and 24 h after the cap was applied. Four women (control group) had a cap without PGE₂. Labour began in 13 women receiving PGE₂, 12 of whom were delivered within 24 h. In these women plasma PGFM rose progressively to levels seen during spontaneous labour, paralleling the changes in cervical dilatation. The increase became significant at 6 h, when cervical dilatation was 4.5 cm (SEM 0.5). Plasma oxytocin also increased significantly while the cap was in place and then decreased. Plasma PGFM and oxytocin did not change in the control subjects, and in the eight women needing further induction of labour the initial rises were transient and not statistically significant.     

Maternal plasma prostaglandin E2 metabolite levels during human pregnancy and parturition

Summary. Because of methodological problems associated with the measurement in biological fluids of both prostaglandin E₂ (PGE₂) and its unstable principal circulating metabolite 13,14-dihydro-15-keto-PGE₂ (PGEM), there is little reliable information on these prostaglandins in human pregnancy and parturition. The recent discovery of a stable PGEM degradation product 11-deoxy-13,14-dihydro-15-keto-11β, 16-cyclo-PGE₂ (bicyclo-PGEM) has provided a means of studying endogenous plasma levels of PGEM which circumvents the problems encountered with direct measurements of PGE₂ and PGEM. Using a radioimmunoassay for bicyclo-PGEM we have therefore determined maternal peripheral plasma PGE₂ metabolite levels during human gestation. PGE₂ metabolite levels did not alter significantly during the second or third trimesters nor during labour. This contrasts with maternal peripheral plasma levels of the principal circulating metabolite of PGF_2α 13,14-dihydro-15-keto-PGF_2α (PGFM) which increases several fold during labour. Compared t o PGE₂ therefore. PGF_2α may be quantitatively the more significant prostaglandin associated with human parturition.     

Changes in 13,14-dihydro-15-keto-prostaglandin F2 alpha and dehydroepiandrosterone-sulfate (DHA-S) levels in amniotic fluid and maternal peripheral venous blood in late pregnancy and during labor

To study the role of prostaglandin (PG) and steroids on the mechanism of parturition, levels of 13,14-dihydro-15-keto-prostaglandin F2 alpha (dhk.PGF2 alpha) and dehydroepiandrosterone-sulfate (DHA-S) in amniotic fluid and plasma during late pregnancy, labor, and puerperium, were measured by radioimmunoassay and gas chromatography-mass spectrometry. Seven patients at term were selected for this study and labor was induced by amniotomy. Amniotic fluid and maternal peripheral blood were obtained simultaneously from each individual at A) the artificial rupture of the membranes before the onset of labor, B) the onset of labor, C) the second stage of labor, D) the delivery, and E) 2 hours postpartum. No increase in either amniotic fluid or plasma dhk-PGF2 alpha was noticed when compared before and at the onset labor. However, there was a steady increase during labor and the maximum was reached at delivery. The dhk-PGF2 alpha concentration in amniotic fluid correlated well with that in maternal plasma. A similar pattern was observed in the DHA-S levels both in amniotic fluid and plasma. No apparent change was observed before the onset of labor, but there was a tendency to increase during labor. A significant correlation between the levels of dhk.PGF2 alpha and DHA-S in amniotic fluid was noticed. From the results obtained above, it is suggested that PG and DHA-S may be involved not in the initiation of labor but in the promotion of parturition. The biological significance of DHA-S on PG levels remains to be clarified.     

Oral Prostaglandins E2 and F2a in the Induction of Labour

Summary: Oral prostaglandins E₂ and F_2a were used to augment amniotomy in the induction of labour in 173 patients. The success rate was significantly higher with prostaglandin E₂ than with prostaglandin F_2a (89% and 75%, respectively). This was achieved despite a significantly lower incidence of gastrointestinal side effects. No serious maternal or fetal complications occurred with either drug. It is concluded that oral prostaglandin E₂ is more efficient than oral prostaglandin F_2a in the induction of labour.     

Controlled study comparing vaginal prostaglandin E2 pessaries with intravenous oxytocin for the stimulation of labour after spontaneous rupture of the membranes

Summary. In a prospective randomized study, 36 patients with spontaneous rupture of the membranes of ≥4 h duration were stimulated with 3 mg vaginal prostaglandin E₂ pessaries or intravenous oxytocin. Oxytocin stimulation was associated with shorter labours and a lower incidence of abnormal cervimetric progress. Of the patients given prostaglandin pessaries, 40% required a second dose after 4 h for slow progress; 45% of the primigravidae subsequently developed abnormal labour which was corrected by augmentation with oxytocin in all cases. One caesarean section was carried out for disproportion, and the remaining 35 patients were delivered vaginally. Prostaglandin pessaries were not associated with an increased incidence of hyperstimulation or sepsis. In conclusion, although PGE₂ pessaries are safe in spontaneous rupture of the membranes, intravenous oxytocin is more efficient in stimulating labour.     

Effect of vacuum curettage on the concentrations of plasma 6-keto-prostaglandin Flα and serum thromboxane B2

Summary. Serial plasma samples collected before and after vacuum curettage followed by methylergometrine injection in 10 women were assayed for 6-keto-prostaglandin F_lα (6-keto-PGF^1α). The mean 6-keto-PGF_lα concentration was 97.2 (SE 8.8) pg/ml before cervical dilatation. The concentration rose to 128.2 (SE 13.5) pg/ml (P < 0.10) immediately and to 133.3 (SE 17.8) pg/ml (P < 0.05) 1 h after curettage and returned to the initial value within 5 h. Neither methylergometrine nor anaesthesia, nor non-gynaecological surgery, caused changes in the level of plasma 6-keto-PGF_lα. The capacity of the platelets to produce thromboxane A² during spontaneous clotting of blood did not change during vacuum curettage, anaesthesia and non-gynaecological surgery, nor after methylergometrine. The evidence suggests that the pregnant myometrium and/or intrauterine tissues capable of generating prostacyclin (PGI₂) in vitro may release PG1₂ also in vivo .     

Primary dysmenorrhoea: the importance of both prostaglandins E2 and F2α

Summary. Menstrual fluid was collected in a contraceptive diaphragm from 16 women with primary dysmenorrhoea and 12 matched control subjects without dysmenorrhoea. Prostaglandins F_2α (PGF_2α), E₂ (PGE₂) and 6-oxo-prostaglandin F_1α (6-oxo-PGF_lα) were extracted and measured using gas-chromatography: mass spectrometry (GC:MS). The concentrations of both PGF_2α and PGE₂ were higher on days 1 and 2 in the dysmenorrhoea group than in the control group and the concentration of PGF_2α was higher on day 1 than on day 2 in the dysmenorrhoea group. The concentrations of 6-oxo-PGF_1α (the stable metabolite of PGI₂) were low in both groups. These results confirm suggestions that PGF_2α is important in the aetiology of dysmenorrhoea and also indicate that PGE₂ may be involved.