Effect of beta-mimetic tocolysis on cervical ripening and plasma prostaglandin F2 alpha metabolite after endocervical application of prostaglandin E2.

To suppress uterine contractions during cervical ripening induced by prostaglandin E2 (PGE2) gel, beta-mimetic drugs were given orally 30 minutes before PGE2 application to 17 patients with unripe cervix. This prevented the increase in contraction frequency observed during the first four hours after PGE2 application in 17 controls. Nevertheless, cervical ripening proceeded at a similar rate and the clinical outcome was comparable in both groups. Prostaglandin E2 application caused a transient rise in plasma levels of the PGE2 alpha metabolite (13,14-dihydro-15-keto), which was not prevented by pretreatment with beta-mimetics. Patients with premature rupture of the membranes had higher initial plasma PGF2 alpha metabolite levels than those with intact membranes but cervical ripening proceeded with the same rate, and the effect of beta-mimetics was the same in both groups. Thus, cervical ripening induced by PGE2 does not depend on uterine contractions, and increased production of PGF2 alpha is unrelated to the ripening process. There was no difference between the three beta-mimetic agents in the present study.