Pregnant women with a short cervix are known to be at increased risk for spontaneous early preterm delivery, but treatment with vaginal progesterone nightly, starting in midgestation, may help reduce the risk, new research suggests.
According to the report [1], prior studies have shown the value of vaginal progesterone for women at increased risk for premature delivery due to a prior premature delivery. However, the authors point out that limiting this treatment to such women is unlikely to have a major impact on rates of premature delivery since just ten per cent of cases occur in this setting.
In the present study, Dr. Kypros H. Nicolaides, from King's College Hospital Medical School, London, and colleagues assessed the delivery outcomes of 250 women with short cervices (15 mm or less as measured at midgestation with transvaginal ultrasound) who were randomized to start using vaginal progesterone or placebo each night beginning at 24 to 34 weeks of gestation.
The rate of spontaneous delivery before 34 weeks of gestation was 34.4 per cent in the control group compared with 19.2 per cent in the intervention group, a risk reduction of 44 per cent. In addition, there was a trend toward reduced neonatal morbidity with progesterone use.
Vaginal progesterone therapy was generally well tolerated and was not associated with any serious adverse effects, Dr. Nicolaides and associates note.
"The findings of our study provide support for a strategy of routine screening of pregnant women by ultrasonographic measurement of cervical length and the prophylactic administration of progesterone to those with a short cervix," they conclude.
However, in a related editorial, Dr. Jim G. Thornton, from the University of Nottingham in the UK, comments that the efficacy and safety of progesterone for reducing preterm delivery in high-risk women is still not known. As such, he cautions that progesterone should not be used to prolong pregnancy outside of a research setting.
He adds that there are at least 14 ongoing trials that should help answer these questions.
[1]
N Engl J Med 2007;357:462-469,499-501.
