Shearman 1963.

Methods	Unit of randomization: pregnancy Method of randomization: unclear. The ampules were said to be coded but who coded these and how women were then allocated to the coded ampules is not stated. Timing of randomization: before the 12th week of gestation Blinding: yes (double) Power calculation: no Number of centers: 2 50 women randomized, 0 women excluded, 50 women analyzed Source of funding: preparations supplied by Schering
Participants	Women having had ≥ 2 consecutive abortions and who had low or falling pregnanediol levels Exclusions: women with uterine malformations Age: not stated Location: London, UK Duration and timing: not stated
Interventions	Up to 8 weeks' gestation: 250 mL/week IM hydroxyprogesterone 8‐11 weeks' gestation: 375 mL/week IM of 17‐a‐hydroxyprogesterone 12‐16 weeks' gestation: 500 mL/week IM of 17‐a‐hydroxyprogesterone 17‐20 weeks' gestation: 375 mg/week IM of 17‐a‐hydroxyprogesterone 21‐24 weeks' gestation: 250 mg/week IM of 17‐a‐hydroxyprogesterone Control: placebo
Outcomes	Miscarriage
Notes	Source of funding: preparations supplied by Schering Dates of study: not stated Funding sources: "the preparations used in this study were made available by Dr. Jurgen Friebel, Schering AG, Berlin" Declarations of interest: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated
Allocation concealment (selection bias)	Unclear risk	Not stated
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Solution A and B ‐ the "correct identity of these substances is not known to any person taking part in this study".
Blinding of outcome assessment (detection bias) All outcomes	Low risk	As above
Incomplete outcome data (attrition bias) All outcomes	Low risk	None
Selective reporting (reporting bias)	Low risk	None
Other bias	Low risk	None