title: Progesterone for the prevention of preterm birth among women at increased risk: a systematic review and meta-analysis of randomized controlled trials.
abstract: OBJECTIVE
  This study was undertaken to determine whether progestational agents, initiated in the second trimester of pregnancy, reduce the risk of delivery less than 37 weeks, among women at increased risk of spontaneous preterm birth.
  
  
  METHODS
  Medline, pre-Medline, EMBASE, and Cochrane Central Register of Controlled Trials were searched. Randomized controlled trials with less than 20% lost to follow-up were included.
  
  
  RESULTS
  Three trials were eligible for inclusion. There was a significant reduction in risk of delivery less than 37 weeks with progestational agents (relative risk [95% CI] = 0.57 [0.36-0.90]). There was no significant effect on perinatal mortality or serious neonatal morbidity.
  
  
  CONCLUSIONS
  Progestational agents, initiated in the second trimester of pregnancy, may reduce the risk of delivery less than 37 weeks' gestation, among women at increased risk of spontaneous preterm birth, but the effect on neonatal outcome is uncertain. Larger randomized controlled trials are required to determine whether this treatment reduces perinatal mortality or serious neonatal morbidity.
authors.affiliation: Department of Obstetrics and Gynaecology, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Toronto, Ontario.
authors.forename: Roberta
authors.initials: R
authors.lastname: Mackenzie
authors.forename: Mark
authors.initials: M
authors.lastname: Walker
authors.forename: Anthony
authors.initials: A
authors.lastname: Armson
authors.forename: Mary E
authors.initials: ME
authors.lastname: Hannah
mesh_terms: D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000209:etiology* / Q000517:prevention & control*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011374:Progesterone / Q000008:administration & dosage* / Q000627:therapeutic use; D011372:Progestins / Q000008:administration & dosage* / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic; D012306:Risk; D012307:Risk Factors
chemical_list: D011372:Progestins; D011374:Progesterone