We’ve known for a while that progesterones can reduce prematurity in certain situations. Intramuscular 17 hydroxy progesterone caproate reduces prematurity in women who have had a previous premature baby. (Meis’s article link below)

Now a systematic review of intravaginal progesterone administration shows that the frequency of preterm birth is reduced in women with a short cervix if they get treatment.  Using  the Individual patient data from 5 RCTs including 775 women Romero et al showed there were fewer preterm deliveries, and fewer extremely preterm deliveries. The relative risk of delivery before 28 weeks was 0.5, i.e. a 50% reduction. For every 18 women treated there would be 1 less infants born before 28 weeks gestation.

The therapy appears to be safe, effective and cheap. Routine cervical length screening and intervention should be standard of care.

Romero R, Nicolaides K, Conde-Agudelo A, Tabor A, O’Brien JM, Cetingoz E, et al. Vaginal progesterone in women with an asymptomatic sonographic short cervix in the midtrimester decreases preterm delivery and neonatal morbidity: a systematic review and metaanalysis of individual patient data. American Journal of Obstetrics and Gynecology. 2012;206(2):124.e1-.e19. http://www.sciencedirect.com/science/article/pii/S0002937811023581

Meis PJ, Klebanoff M, Thom E, Dombrowski MP, Sibai B, Moawad AH, et al. Prevention of Recurrent Preterm Delivery by 17 Alpha-Hydroxyprogesterone Caproate. N Engl J Med. 2003;348(24):2379. http://www.nejm.org/doi/full/10.1056/NEJMoa035140