Progesterone and preterm birth prevention: translating clinical trials data into clinical practice.

OBJECTIVE: We sought to provide evidence-based guidelines for using progestogens for the prevention of preterm birth (PTB).
METHODS: Relevant documents, in particular randomized trials, were identified using PubMed (US National Library of Medicine, 1983 through February 2012) publications, written in English, which evaluate the effectiveness of progestogens for prevention of PTB. Progestogens evaluated were, in particular, vaginal progesterone and 17-alpha-hydroxy-progesterone caproate. Additionally, the Cochrane Library, organizational guidelines, and studies identified through review of the above were utilized to identify relevant articles. Data were evaluated according to population studied, with separate analyses for singleton vs multiple gestations, prior PTB, or short transvaginal ultrasound cervical length (CL), and combinations of these factors. Consistent with US Preventive Task Force suggestions, references were evaluated for quality based on the highest level of evidence, and recommendations were graded. RESULTS AND RECOMMENDATIONS: Summary of randomized studies indicates that in women with singleton gestations, no prior PTB, and short CL ≤ 20 mm at ≤ 24 weeks, vaginal progesterone, either 90-mg gel or 200-mg suppository, is associated with reduction in PTB and perinatal morbidity and mortality, and can be offered in these cases. The issue of universal CL screening of singleton gestations without prior PTB for the prevention of PTB remains an object of debate. CL screening in singleton gestations without prior PTB cannot yet be universally mandated. Nonetheless, implementation of such a screening strategy can be viewed as reasonable, and can be considered by individual practitioners, following strict guidelines. In singleton gestations with prior PTB 20-36 6/7 weeks, 17-alpha-hydroxy-progesterone caproate 250 mg intramuscularly weekly, preferably starting at 16-20 weeks until 36 weeks, is recommended. In these women with prior PTB, if the transvaginal ultrasound CL shortens to < 25 mm at < 24 weeks, cervical cerclage may be offered. Progestogens have not been associated with prevention of PTB in women who have in the current pregnancy multiple gestations, preterm labor, or preterm premature rupture of membranes. There is insufficient evidence to recommend the use of progestogens in women with any of these risk factors, with or without a short CL.