17P Not Effective Once Preterm Labor Begins



DALLAS – Biweekly injections of 17-alpha-hydroxyprogesterone caproate, or 17P, did not significantly prolong pregnancy in a randomized open-label French study involving 188 women with an episode of successfully arrested preterm labor and a short cervix.

The median time from randomization to delivery was 64 days in 94 women who received 17P, and 67 days in 94 control subjects, Dr. Patrick Rozenberg reported at the annual meeting of the Society for Maternal-Fetal Medicine.

The rates of delivery prior to 37, 34, and 32 weeks’ gestation also did not differ significantly between the groups, with 39% and 38%, 16% and 20%, and 9% and 14% in the treatment and control groups, respectively, delivering at those time points, said Dr. Rozenberg of Poissy (France) Saint-Germain Hospital.

The findings contrast with those from several smaller trials that suggested 17P might reduce the risk of preterm delivery in women with preterm labor arrested by tocolysis.

Women in the current study had singleton pregnancies at 24-32 weeks’ gestation and a cervical length less than 25 mm, and were admitted at one of 13 French university hospitals with preterm labor. All were successfully treated with 12 mg of intramuscular betamethasone, which was repeated after 24 hours. The women were then randomized to receive or not receive 17P.

The 17P treatment group received 500 mg of intramuscular 17P beginning after tocolysis ended, and then twice weekly until 36 weeks’ gestation or until delivery. The control group received no progesterone, but all other management in both groups was left to the discretion of the attending physician, Dr. Rozenberg said, noting that clinical characteristics, including gestational age and cervical length, were similar in both the treatment and control groups, as were additional management, need for readmission for preterm labor, and tocolysis.

Neonatal outcomes, including birth weight and complications, also were similar between the groups, and there were no adverse effects associated with treatment.

Although several studies suggest that progesterone can reduce the rate of prematurity, many questions remain about optimal timing, mode of administration, dosing, and indications, Dr. Rozenberg noted. The findings of this study, however, do not support its use in women with a short cervix and an episode of preterm labor successfully treated with tocolysis.

"We could say that treatment with progesterone in patients with preterm labor and a short cervix below 25 mm did not prolong pregnancy, did not reduce the rate of prematurity and related complications, and was not associated with adverse effects. In conclusion, once the pathologic process of preterm labor begins, progesterone is no longer effective," he said.

Dr. Rozenberg said he had no relevant financial disclosures.

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