Prostaglandins and pre-eclampsia [letter]

Professor Brosens and colleagues (April 27 p.808) questions the safety of prostaglandins (PGs) for the induction of labor when pregnancy is complicated by hypertensive states especially preeclampsia. Objections are based on the possibility that the uteroplacental bloodflow which may already be compromised in these situations could be further reduced by vasoconstrictive effects of the PGs on uterine placental and umbilical vessels. We have been using PGs extensively in this department and for the past year have been carrying out a double-blind trial of PGE2 and oxytocin by intravenous infusion after amniotomy for induction of labor in primigravidae. In 23 of the patients included thus far labor was induced between 36 and 38 weeks because of moderate or severe preeclampsia. Of these 12 have received oxytocin and 11 PGE2. In all cases elective epidural analgesia has been employed and continuous fetal heartrate and intrauterine pressure recordings performed throughout. 1 patient in the group required an emergency cesarean section because of fetal distress; 2 others (1 from each group) were delivered by cesarean section because of failure to progress in labor. The remainder delivered vaginally with no evidence of increased incidence of fetal distress in the PG group. No perinatal deaths occurred. In an additional 18 primigravidae labor was induced at 36-38 weeks because of hypertensive complications of pregnancy by local PGE2 administration as previously described. These patients were assessed as clinically unfavorable for induction. 2 patients developed fetal distress and required cesarean sections; the others delivered vaginally. Experience with PGF2alpha is much less extensive but there is no reason to believe that this compound would behave differently except with regard to maternal side effects. Thus it seems beneficial to use PGs for inducing labor in pregnancies complicated by hypertension and preeclampsia; no evidence of the suggested theoretical hazards has been seen. The suggested dangers may be questioned on 2 bases. It seems premature based on existing knowledge to infer that spiral arteries in hypertensive pregnancies are adversely affected by vasoconstrictor substances. Also it is probable that high concentrations of PGs occur naturally in reproductive tissues and a rapid increase of PG in amniotic fluid occurs in spontaneous labors as well as those induced with oxytocin or PGs. Due caution must be exercised in using PGs where placental function may be impaired. The results-to-date which have been obtained with careful monitoring of the fetal heartrate and intrauterine pressure show no evidence of adverse effects on the fetus as a result of PG use in preeclampsia and suggest they represent a valuable therapeutic agent in the management of this condition. (authors modified)