Comparison of oestradiol and prostaglandin E2 vaginal gel for ripening the unfavourable cervix

Abstract

Mr. P.M. Tromans and others (February 28 p. 679) found that estradiol applied vaginally was a safe and effective method for ripening the unfavorable cervix prior to induction of labor. Before estradiol is used generally for this purpose we would like to call attention to a possible side effect of estradiol that we have observed in the babies--namely neonatal hyperbilirubinemia during the 1st week of life. In a double-blind prospective study of 50 primiparous women with a Bishop score below 5 we investigated the effect of estradiol on induction of labor and cervical ripening. In 25 women 115 mg 17beta-estradiol was instilled into the extraamniotic space (estradiol group) through a Foley catheter with 40 ml water in the balloon. The catheter was left in utero after the instillation. In the remaining 25 women a sterile 0.9% saline solution was instilled (saline group). Otherwise the procedure was the same. After the instillation all women took oxytocin tablets every 30 minutes for 5 hours. 18 hours after instillation (next morning) delivery was completed in 15 women in the estradiol group and 17 women in the saline group; in the rest of the women the median Bishop score was 7.5 in both groups. A significant rise in the serum concentration of estradiol was seen in the women in the estradiol group and during the hours after the instillation the serum concentrations of estradiol were significantly higher in the estradiol group than in the saline group. Serum concentrations of estradiol in the umbilical veins at the time of birth were the same in the 2 groups. Phototherapy was given to 13 infants in the estradiol group and 4 infants in the saline group because of neonatal hyperbilirubinemia (serum bilirubin >200 mcmol/l (11.7 mg/100 ml) during the 1st week of life). The observed difference between the groups may be due to random variation but the possibility of that is less than 0.02 (Fishers exact test 2-tailed). We therefore think that this possible connection between estradiol and neonatal hyperbilirubinemia should be investigated further in controlled clinical trials before estradiol is suggested as a safe drug for cervical ripening. (Authors modified)