Progesterone and the risk of preterm birth among women with a short cervix.
BACKGROUND
Previous randomized trials have shown that progesterone administration in women who previously delivered prematurely reduces the risk of recurrent premature delivery. Asymptomatic women found at midgestation to have a short cervix are at greatly increased risk for spontaneous early preterm delivery, and it is unknown whether progesterone reduces this risk in such women.


METHODS
Cervical length was measured by transvaginal ultrasonography at a median of 22 weeks of gestation (range, 20 to 25) in 24,620 pregnant women seen for routine prenatal care. Cervical length was 15 mm or less in 413 of the women (1.7%), and 250 (60.5%) of these 413 women were randomly assigned to receive vaginal progesterone (200 mg each night) or placebo from 24 to 34 weeks of gestation. The primary outcome was spontaneous delivery before 34 weeks.


RESULTS
Spontaneous delivery before 34 weeks of gestation was less frequent in the progesterone group than in the placebo group (19.2% vs. 34.4%; relative risk, 0.56; 95% confidence interval [CI], 0.36 to 0.86). Progesterone was associated with a nonsignificant reduction in neonatal morbidity (8.1% vs. 13.8%; relative risk, 0.59; 95% CI, 0.26 to 1.25; P=0.17). There were no serious adverse events associated with the use of progesterone.


CONCLUSIONS
In women with a short cervix, treatment with progesterone reduces the rate of spontaneous early preterm delivery. (ClinicalTrials.gov number, NCT00422526 [ClinicalTrials.gov].).
Fonseca
Eduardo B
EB
Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, United Kingdom.
Celik
Ebru
E
Parra
Mauro
M
Singh
Mandeep
M
Nicolaides
Kypros H
KH
D000282:Administration, Intravaginal; D000328:Adult; D002584:Cervix Uteri / Q000033:anatomy & histology*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D011247:Pregnancy; D011256:Pregnancy Outcome; D011272:Pregnancy, Multiple; D047928:Premature Birth / Q000517:prevention & control*; D011374:Progesterone / Q000627:therapeutic use*; D012306:Risk
D011374:Progesterone