Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Adverse effects
Systematic review	Pregnant women Data from 1 RCT	Fetal genital tract abnormalities/virilisation 0/71 (0%) with oral dydrogesterone 0/34 (0%) with no treatment	OR not estimable The RCTs had weak methods (see Further information on studies)		Not significant
Systematic review	Pregnant women Data from 1 RCT	Fetal genital tract abnormalities/virilisation 0/11 (0%) with IM hydroxyprogesterone 0/7 (0%) with placebo	OR not estimable The RCT had weak methods (see Further information on studies)		Not significant
Systematic review	Pregnant women Data from 1 RCT	Neonatal death 2/71 (2.8%) with oral dydrogesterone 1/34 (2.9%) with no treatment	OR 0.96 95% CI 0.08 to 11.00 The RCTs had weak methods (see Further information on studies)		Not significant
Systematic review	Pregnant women Data from 1 RCT	Neonatal death 1/49 (2%) with progesterone pellets 0/40 (0%) with no treatment	OR 6.15 95% CI 0.12 to 316.22 The RCTs had weak methods (see Further information on studies)		Not significant
Systematic review	Pregnant women Data from 1 RCT	Preterm birth 5/71 (7%) with oral dydrogesterone 3/34 (9%) with no treatment	OR 0.78 95% CI 0.17 to 3.61 The RCTs had weak methods (see Further information on studies)		Not significant
Systematic review	Pregnant women Data from 1 RCT	Preterm birth 1/18 (6%) with oral medroxyprogesterone 1/26 (4%) with placebo	OR 1.47 95% CI 0.08 to 25.46 The RCTs had weak methods (see Further information on studies)		Not significant
Systematic review	Pregnant women Data from 1 RCT	Preterm birth 6/11 (55%) with IM hydroxyprogesterone 3/7 (43%) with placebo	OR 1.56 95% CI 0.25 to 9.81 The RCTs had weak methods (see Further information on studies)		Not significant
Systematic review	Pregnant women Data from 1 RCT	Preterm birth 2/49 (4%) with progesterone pellets 1/40 (3%) with no treatment	OR 1.62 95% CI 0.16 to 16.14 The RCTs had weak methods (see Further information on studies)		Not significant