Study shows: Vaginal gel reduces rate of preterm birth in some at-risk women

Progesterone gel applied vaginally reduced the rate of preterm birth by 45% in women identified with a short cervix, one of many risk factors for premature birth

Managing Editor, OBG MANAGEMENT

A National Institutes of Health study has found that progesterone gel reduces the rate of early preterm delivery—before 33 weeks—by 45% in women with a short cervix. The study was published this month in the online edition of Ultrasound in Obstetrics and Gynecology.¹

Using progesterone to decrease the risk of preterm birth in women with a short cervix is not new; injections of synthetic progesterone have been used for years for this indication. However, the use of progesterone gel to treat women with a short cervix is a recent innovation.

Women who have a short cervix can be identified through routine ultrasonography screening. “Sonographic cervical length is the most powerful predictor for preterm birth in the index pregnancy,” says Roberto Romero, MD, program head for Perinatology Research and Obstetrics and chief of the Perinatology Research Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), and “is more informative than is a history of previous preterm birth.”²

For phyiscians’ practices, the findings of the study suggest that a combined approach is valuable:

• sonographic screening of women for transvaginal cervical length in the midtrimester

• intervention for at-risk patients identified with a short cervix.

“The administration of vaginal progesterone gel can reduce the frequency of preterm birth,” according to the research team, “and improve neonatal outcome, safely and conveniently”.

After sonographic examination, 458 women who had a short cervix (between 10 and 20 mm in length) were randomized to receive either a gel progesterone preparation or placebo between gestational weeks 19 and 23. Both preparations were applied daily to the vagina.

Results showed that progesterone gel was associated with a lower rate of preterm delivery at less than 33 weeks (8.9% in progesterone gel group vs. 16.1% in placebo group). In addition, infants born to women who used the progesterone gel had a lower rate of respiratory distress syndrome (3%) than those in the placebo group (7.6%). A difference in the rate of preterm birth was also seen in births that occurred before 28 and 35 weeks’ gestation.¹

Vaginal progesterone gel was well tolerated in the study, and adherence was substantial (>90%).²

Once a woman is identified as having a short cervix, she can apply the gel at a cost of $10 to $15 a day.

The compound used in this study, identical to natural progesterone, is already FDA-approved as a supplemental treatment for women attempting to conceive with in vitro fertilization, and has a known safety margin when used daily. It is not yet FDA-approved for use in women at risk of premature birth.

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