General Obstetrics and Gynecology Obstetrics
Prophylactic administration of progesterone by vaginal suppository to reduce the incidence of spontaneous preterm birth in women at increased risk: A randomized placebo-controlled double-blind study,☆☆

https://doi.org/10.1067/mob.2003.41Get rights and content

Abstract

Objective: The purpose of this study was to evaluate the effect of prophylactic vaginal progesterone in decreasing preterm birth rate in a high-risk population. Study design: A randomized, double-blind, placebo-controlled study included 142 high-risk singleton pregnancies. Progesterone (100 mg) or placebo was administered daily by vaginal suppository and all patients underwent uterine contraction monitoring with an external tocodynamometer once a week for 60 minutes, between 24 and 34 weeks of gestation. Progesterone (n = 72) and placebo (n = 70) groups were compared for epidemiologic characteristics, uterine contraction frequency, and incidence of preterm birth. Data were compared by χ2 analysis and Fisher exact test. Results: The preterm birth rate was 21.1% (30/142). Differences in uterine activity were found between the progesterone and placebo groups (23.6% vs 54.3%, respectively; P < .05) and in preterm birth between progesterone and placebo (13.8% vs 28.5%, respectively; P < .05). More women were delivered before 34 weeks in the placebo group (18.5%) than in the progesterone group (2.7%) (P < .05). Conclusion: Prophylactic vaginal progesterone reduced the frequency of uterine contractions and the rate of preterm delivery in women at high risk for prematurity. (Am J Obstet Gynecol 2003;188:419-24.)

Section snippets

Material and methods

This study was performed in the Obstetrics Clinic, at Hospital das Clinicas, University of Sao Paulo Medical School, a tertiary medical center, in Brazil. A consent form was signed after detailed information was given to every pregnant women. The study was approved by the Ethical Commission of this hospital.

Data available at the start of the study showed that the preterm birth rate in the Obstetrics Clinic, Hospital das Clinicas, University of Sao Paulo Medical School, was 25%.12 Although some

Results

Of 142 cases, there were 30 preterm births (21.1%). The incidence of preterm delivery in the progesterone group was 13.8% (10/72) and 28.5% (20/70) in the placebo group. When comparing these two groups, we observed a statistically significant difference in the preterm delivery rate (P = .03).

As shown in Table II, the two groups were found similar in regard to age, risk factors for preterm delivery, and obstetric history.

. Characteristics of women at randomization

Empty CellPlacebo (n = 70)Progesterone (n =

Comment

The results of this study confirm the findings of other studies reporting that progesterone is effective in preventing preterm delivery.20, 21, 22, 23, 24 The real mechanism of action of this drug is not well known; however, its clinical usefulness was shown in our study by the decrease in the incidence of preterm birth from 28.1% in the placebo group to 13.8% in the progesterone group.

The difference between the two groups could not be explained in terms of epidemiologic characteristics,

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    Supported by FAPESP.

    ☆☆

    Reprint requests: Eduardo B. da Fonseca, MD, University of Sao Paulo Medical School, Obstetric Clinic, Av 11 de junho, 1006 apto 133, Vila Clementino, Sao Paulo-SP, 04041-003, Brazil. E-mail: [email protected]

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