Is progesterone effective in preventing preterm birth?
A meta-analysis study published in the American Journal of Obstetrics and Gynecology provides additional validation for using progesterone to reduce the risk of preterm birth (PTB), neonatal complications and infant mortality in pregnant women with a short cervix. The researchers used individual patient data and found that vaginal progesterone reduces the rate of PTB in singleton pregnancies and would also be cost effective.
Looking at data from five randomized controlled trials that compared vaginal progesterone vs. placebo or no treatment, the researchers used individual patient data for 974 women with a cervical length £ 25 mm. Of those 974 women, 498 were assigned to vaginal progesterone and 476 to placebo. Two of the trials analyzed were specifically designed to evaluate use of vaginal progesterone in women with a short cervix (cervical length £ 15 mm and cervical length between 10 and 20 mm). One study tested the effect of vaginal progesterone in at-risk women for PTB because of previous spontaneous preterm pregnancies (SPTB). Another study evaluated use of vaginal progesterone in women at risk for PTB because of previous SPTB, a positive fibronectin test, or a sonographic cervical length £ 25 mm. The last study looked at use of vaginal progesterone in women with a history of SPTB, uterine malformations, or twin gestations. Three studies provided 96% of the total sample size of the individual patient data meta-analysis.
The researchers found that vaginal progesterone significantly reduced the risk of PTB birth < 33 weeks’ gestation (14% vs 22%; RR 0.62, 95% CI 0.47 – 0.81). The total frequencies of giving birth < 36, < 35, < 34, < 32, < 30, and < 28 weeks’ gestation and SPTB at < 33 and < 34 weeks were also significantly lower in the vaginal progesterone group (RRs from 0.64 to 0.80). Also in the vaginal progesterone group, the mean gestation age at delivery was significantly greater than in the placebo group (mean difference 0.74 weeks, 95% CI 0.18-1.30). The authors noted that vaginal progesterone treatment was associated with a significant decrease in risk of respiratory distress syndrome, composite neonatal morbidity, very low birthweight (< 1500 and < 2500 g) and admission to the neonatal intensive care unit. The frequency of neonatal mortality was 1.4% (7/498) in the vaginal progesterone group and 3.2% (15/476) in the placebo group.
The authors also reviewed cost-effectiveness studies on vaginal progesterone and found that measuring the uterine cervix with ultrasound in mid-trimester and giving vaginal progesterone to patients with a short cervix is a cost-effective strategy. One evaluated study estimated that it would save approximately $19.6 million for every 100,000 women screened.