Catherine Y. Spong, MD Dr. Spong is Chief of the Pregnancy and Perinatology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md.
In a systematic review of 11 trials (2,425 women and 3,187 infants) involving the use of progesterone to prevent preterm birth in high-risk women—including those who had a history of preterm birth, those carrying a multiple gestation, and those with a short cervix—Dodd and colleagues found mixed results.10 Progesterone reduced the rate of preterm birth before 34 weeks’ gestation in women who had a history of preterm birth, as well as in those who had a short cervix, but no improvement was seen in women carrying a multiple gestation.
A cumulative meta-analysis by Coomarasamy and colleagues found that progestogens significantly reduce the rate of preterm birth, a benefit that was evident beginning in 1975.1
The most recent Committee Opinion from the American College of Obstetricians and Gynecologists25 concludes that “it is important to offer progesterone for pregnancy prolongation to only women with a documented history of a previous spontaneous birth at less than 37 weeks of gestation.” The opinion also takes into account the findings of the Fonseca trial in regard to women who have a short cervix,14 and concludes that “progesterone supplementation may be considered for use in asymptomatic women with a short cervix.”
Trials of other high-risk groups, including women who have a positive fibronectin test, bleeding, or iatrogenic preterm labor, are needed. The fact that progesterone supplementation is not universally effective in women who have a history of preterm birth suggests that not all pathways leading to preterm birth are ameliorated by progesterone therapy. Given the many similarities between women who have a history of preterm birth and women who have a short cervix, evidence may ultimately be available to support the benefits of progesterone in both situations. However, the lack of a benefit in women carrying a multiple gestation likely reflects the different underlying mechanism in that group.
CASE: RESOLVED
You discuss with Ms. Jones the options available to reduce the likelihood of recurrent preterm birth. She opts for progesterone supplementation, which is initiated at 16 weeks’ gestation, with no restrictions on activity. A sonogram at 18 weeks reveals normal anatomy and a cervical length of 4 cm.
At 22 weeks’ gestation, Ms. Jones visits the labor and delivery unit complaining of leaking fluid. You perform a sterile speculum exam, which is negative, monitor her for several hours, and send her home.
At 26 weeks, the patient experiences contractions and is again evaluated. An examination reveals the cervix to be long and closed. After prolonged monitoring, Ms. Jones is again sent home.
At 37 weeks’ gestation, the patient reports another episode of leaking fluid. This time, a sterile speculum exam is positive, and you begin induction of labor.
Labor proceeds smoothly, and Ms. Jones delivers a 3,100-g infant. The newborn has an Apgar score of 8 and 9 at 1 and 5 minutes, respectively.
