Table 1.

Overview of the studies published by authors consulted when planning the IPD meta-analysis

Study	Period	N	Intervention	Primary outcome
Briery[11]	06/04-06/10	30	250 mg 17-OPHC or placebo	delivery before 35 completed weeks' of gestation
Cetingoz[10]	12/04-02/07	67	100 mg vaginal progesterone or placebo	delivery before 37 weeks
Lim[12]	08/06-07/09	654	250 mg 17-OHPC in 1 mL castor oil or placebo	composite outcome (Severe RDS, BPD, IVH grade III or worse, NEC, proven sepsis or death before discharge)
Combs[7]	11/04-02/10	240	250 mg 17-OHPC or placebo	composite outcome (RDS, Oxygen therapy at 28d, Neonatal sepsis, Pneumonia, IVH grade III or worse, periventricular leukomalacia, NEC, retinopathy of prematurity, asphyxia)
Nassar[13]	10/06-10/10	290	250 mg 17-OPHC or placebo	frequency of delivery prior to completed 37 weeks of gestation (259 days)
Norman[9]	12/04-04/08	500	Vaginal progesterone gel 90 mg or placebo	delivery or intrauterine death before 34 weeks of gestation
Rode[14]	06/06-09/10	650	200 mg vaginal progesterone of placebo	incidence of delivery < 34 weeks
Rouse[8]	04/04-02/06	661	250 mg 17-OHPC in 1 mL castor oil or placebo	composite outcome (delivery or fetal death before 35 completed weeks of gestation)
Rozenberg[15]	06/06-06/10	160	500 mg 17-OPHC or no treatment	Interval between inclusion and delivery
Serra[16]	01/06-05/08	246	200 mg or 400 mg vaginal progesterone or placebo	Preterm birth rate (< 37 weeks)