Response of the Pregnant Human Uterus to Low and High Doses of Prostaglandin E₁ and E₂

Abstract

Uterine sensitivity to low doses of prostaglandin E, was compared at midpregnancy and at term. An analysis of the amniotic pressure recordings revealed that the uterus in midpregnancy responded by increased contractility to an infusion rate of the same order as that, commonly used for induction of labour at term. However, the absolute intensity of the contractions was significantly higher at term than at midpregnancy. Intravenous infusion of high doses of prostaglandin E, (maximum dose without consistent subjective side effects) at midpregnancy stimulated the uterus to frequent contractions (6-8 contractions per 10 min) of gradually increasing intensity, which reached an average value of 35 mmHg following 6 hours of infusion. T h e individual uterine response to prostaglandin varied considerably from one case to another. The "maximum tolerable infusion rate" which could be administered without major subjective side effects also varied within a wide range.

Cervical Ripening with Intracervical Prostaglandin-E2 Gel

“…Eight of 10 group A patients and all 5 Group B patients had an increase in uterine activity soon after the gel application consisting of low amplitude, high frequency contractions as described by Roth-Brandel. 8 No significant increase in uterine tonus was observed, and none of the patients reported painful contractions after application of the gel. In 2 of 10 Group A patients, regular contractions started 30 minutes after treatment and continued during the observation period; in others, the contractions subsided within 2 to 4 hours.…”

Prostaglandins

“…Using pregnant human myometrium, Embrey and Morrison (241) reported that both PGEz and PGFz, stimulated myometrial contractility in vitro. In vivo administration of PGEI, PGE2, PGFl,, and PGF2, had a stimulatory effect on the uterus (242)(243)(244)(245). In vivo administration of PGEI, PGE2, PGFl,, and PGF2, had a stimulatory effect on the uterus (242)(243)(244)(245).…”