Prostaglandin E and F2 alpha concentration in the cervical mucus and mechanism of cervical ripening.

Objective: To study the mechanism of cervical ripening by determination of prostaglandin E (PGE) and F2 alpha (PGF2 alpha) concentrations in cervical mucus during the course of pregnancy.

Study Design: Cervical mucus was collected from 99 pregnant women attending the mother care unit of the department. Women with sexual intercourse within the last 24 hours before sampling and subjects with bacterial vaginosis were analysed separately.

Results: Eleven women had sexual intercourse within 24 hours before sampling. The concentration of PGE in their cervical mucus was high corresponding to 2000-4000 pg/mg w w lasting for a period of 10-12 hours postcoitally, whereas the levels of PGF 2 alpha only increased slightly. Bacterial vaginosis was accomplished by a slight but significant elevation of PGF2 alpha levels but only of a minor increment of the PGE values. The prostaglandin concentrations in the mucus from the remaining 68 women were for PGE 102.75 +/- 111.51 and for PGF2 alpha 97.54 +/- 82.48 pg/mg w w (mean +/- SD). Although the values were scattered the concentrations remained at approximately the same level throughout pregnancy and there was no tendency towards an increment during the last weeks of pregnancy when cervical maturation is apparent.

Conclusion: Cervical softening seems not to be accomplished by a massive local release of prostaglandins but rather the result of a number of different mechanisms more or less influenced by minor alterations of prostaglandin synthesis and release. Involved in these mechanisms are probably neutrophil-derived collagenases.