Study	Reason for exclusion
Berle 1980	Included women who "presented with bleeding" of threatened miscarriage, wrong population
Brenner 1962	Outcomes of this study were not applicable to this review. Treatment was not given to women until 38 weeks' gestation. The outcome measured was time from onset of labor to delivery
Check 1985	No method of randomization was used for this trial.
Check 1987a	No method of randomization was used for this trial.
Check 1987b	It is unclear as to whether there was any randomization. The authors of this review attempted, but failed, to contact the trial authors.
Check 1995	The intervention considered in this trial is progesterone in association with immunotherapy rather than progesterone alone.
Clifford 1996	In this trial, progesterone was not taken during pregnancy.
Corrado 2002	Trial of women undergoing amniocentesis, not with recurrent miscarriage
Daya 1988	This trial was not an RCT.
Fuchs 1966	This trial was terminated before the results were of sufficient size to statistically analyze. Therefore, data are incomplete.
Gerhard 1987	Trial of women with threatened miscarriage.
Johnson 1975	The outcome measure of this trial was preterm delivery rather than miscarriage.
Kyrou 2011	Comparison of stopping progestin at 12 weeks vs continuing. Wrong comparison
Moller 1965	Trial of women with threatened miscarriage.
Norman 2006	This trial was excluded because progesterone was given after 20 weeks' gestation to prevent preterm labor.
Nyboe Anderson 2002	Trial of women after IVF or ICSI, not with recurrent miscarriage
Prietl 1992	The active intervention given in this trial was a combination of progesterone and oestrogen, rather than progesterone alone
Rock 1985	This trial was not an RCT.
Shu 2002	Wrong population and intervention
Sidelnikova 1990	This trial was not an RCT.
Smitz 1992	This trial compared intramuscular progesterone versus intravaginal progesterone in the luteal phase followed by all participants receiving progesterone and oestrogen on the day prior to ovocyte puncture. There was no placebo or 'no treatment' control and the treatment given after commencement of pregnancy was a combination of progesterone and oestrogen rather than progesterone alone.
Sondergaard 1985	This trial was conducted to ascertain the efficacy of progesterone to prevent preterm birth rather than miscarriage.
Tognoni 1980	Trial of women with threatened miscarriage.
Turner 1966	The outcome of this trial is not relevant to the current systematic review. Progesterone was not given to prevent miscarriage and was not given until the 30/40.

ICSI: intracytoplasmic sperm injection; IVF: in vitro fertilisation; RCT: randomized controlled trial; VS: versus