ACOG (2003). ACOG Committee Opinion. Use of progesterone to reduce preterm birth. Obstetrics and Gynecology, 102(5 Pt 1), 1115-1116. https://doi.org/10.1016/j.obstetgynecol.2003.09.032
ACOG. ACOG Committee Opinion. Use of progesterone to reduce preterm birth. Obstet Gynecol. 2003;102(5 Pt 1):1115-1116. doi:10.1016/j.obstetgynecol.2003.09.032
ACOG. "ACOG Committee Opinion. Use of progesterone to reduce preterm birth." Obstetrics and Gynecology, vol. 102, no. 5 Pt 1, 2003, pp. 1115-1116.
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RRM Academy Synopsis
Progesterone may reduce repeat preterm birth in select high-risk women
A 2003 ACOG committee opinion reports that two trials support the hypothesis that progesterone supplementation may lower preterm birth in a selected group of high-risk women. The NICHD trial enrolled 459 women with an earlier spontaneous preterm birth. On weekly 17P injections, 36 out of 100 gave birth before 37 weeks, against 55 out of 100 on placebo.
Study at a glance, randomized, placebo-controlled trials of 459 women: Progesterone may reduce repeat preterm birth in select high-risk women. Source: ACOG, 2003, PMID 14672496.
Key Findings
Of 459 women with a documented previous spontaneous birth before 37 weeks, 306 received weekly 17 alpha-hydroxyprogesterone caproate (17P) injections and 153 received placebo. The trial stopped early.
Preterm birth before 37 weeks occurred in 36.3% of the progesterone group and 54.9% of the placebo group (relative risk 0.66, confidence interval 0.54-0.81, P = .0001).
Before 35 weeks the rates were 20.6% against 30.7% (relative risk 0.67, confidence interval 0.48-0.93). Before 32 weeks they were 11.4% against 19.6% (relative risk 0.58, confidence interval 0.37-0.91).
In a small randomized placebo-controlled trial of 142 women at high risk, delivery before 34 weeks occurred in 2.7% given vaginal progesterone and 18.6% given placebo.
The committee advises restricting progesterone to women with a documented previous spontaneous birth before 37 weeks, citing unresolved questions about the route of delivery and long-term safety.
Interpretation
This is a committee opinion from ACOG's Committee on Obstetric Practice, drawing on two randomized, placebo-controlled trials. The larger trial stopped early, showing strong protection against repeat preterm birth. The smaller trial enrolled women with other high-risk markers, such as an earlier preterm birth, a cervical cerclage, or a uterine malformation. The committee notes that the best progesterone formulation is still unresolved. The findings support further trials of progesterone in other high-risk groups, including twin pregnancies, a short cervix, and a positive fetal fibronectin result.
RRM Context
The larger trial tested 17P, a synthetic progestin, and the smaller trial used vaginal progesterone, the body's own hormone. The opinion groups both as progesterone supplementation. Restorative reproductive medicine separates them. It starts from the ovulatory cycle, when the body makes its own progesterone.
Our editorial summary of this paper, not the article's abstract.
Abstract
Preterm birth affects 12% of all births in the United States. Recent studies support the hypothesis that progesterone supplementation reduces preterm birth in a select group of women (ie, those with a prior spontaneous birth at <37 weeks of gestation). Despite the apparent benefits of progesterone in this high-risk population, the ideal progesterone formulation is unknown. The American College of Obstetricians and Gynecologists Committee on Obstetric Practice believes that further studies are needed to evaluate the use of progesterone in patients with other high-risk obstetric factors, such as multiple gestations, short cervical length, or positive test results for cervicovaginal fetal fibronectin. When progesterone is used, it is important to restrict its use to only women with a documented history of a previous spontaneous birth at less than 37 weeks of gestation because unresolved issues remain, such as optimal route of drug delivery and long-term safety of the drug.
