Study	Reason for exclusion
Abuhamad 1999	This abstract compares TRH + betamethasone with betamethasone + placebo.
Althabe 2015	This is a trial of strategies to optimise use of corticosteroids.
Asnafei 2004	This study is quasi‐experimental.
Butterfill 1979	Randomised participants are combined with a non‐randomised cohort and cannot be analysed separately.
Dola 1997	This abstract compares TRH + betamethasone with betamethasone + placebo.
Egerman 1998	This trial compares oral vs IM dexamethasone in the prevention of RDS. It does not meet our entry criteria for inclusion of studies for the review.
Garite 1981	This trial compares a policy of corticosteroid therapy followed by elective delivery with a policy of withholding corticosteroids and awaiting delivery so the independent effect of the 2 co‐interventions cannot be evaluated separately.
Grgic 2003	Not a randomised trial. Outcomes for women who received steroids were compared with those that did not. Information obtained from translation sheet. Original article in Bosnian
Halac 1990	Not a randomised trial. Women were allocated to placebo if they were expected to deliver within 24 h and to betamethasone if labour was not expected within 24 h.
Iams 1985	Corticosteroid therapy (hydrocortisone) and co‐intervention of elective delivery was compared to expectant management in PROM. The independent effect of the 2 co‐interventions cannot be evaluated separately.
Khandelwal 2012	Compared different doses of corticosteroid: 12‐hourly vs 24‐hourly. The study includes a repeat dose of corticosteroids and is eligible for inclusion in a different review, 'Repeat doses of prenatal corticosteroids for women at risk of preterm birth for improving neonatal health outcomes' Crowther 2015.
Koivisto 2007	The study includes a repeat dose of corticosteroids and is eligible for inclusion in a different review, 'Repeat doses of prenatal corticosteroids for women at risk of preterm birth for improving neonatal health outcomes' Crowther 2015.
Kuhn 1982	Randomised participants are combined with a non‐randomised cohort and cannot be analysed separately.
Kurtzman 2008	The study includes a repeat dose of corticosteroids and is eligible for inclusion in a different review, 'Repeat doses of prenatal corticosteroids for women at risk of preterm birth for improving neonatal health outcomes' Crowther 2015.
Liu 2006	Quasi‐randomised study that allocated women according to the in‐patient sequence. Compared the effect of dexamethasone combined with vitamin K, dexamethasone alone and no dexamethasone or vitamin K on periventricular/intraventricular haemorrhage.
Magee 1997	This study compares the effects of betamethasone vs dexamethasone on antenatal fetal heart rate.
Maksic 2008	This study appears to be an observational study of 163 premature infants, 80 of whom were exposed to antenatal corticosteroids, and 83 of whom were not.
McEvoy 2010	This trial compares repeat dose corticosteroids and is eligible for inclusion a different review, 'Repeat doses of prenatal corticosteroids for women at risk of preterm birth for improving neonatal health outcomes' Crowther 2015.
Minoui 1998	This study compares the effects of betamethasone vs dexamethasone on antenatal fetal heart rate.
Morales 1986	Quasi‐randomised using medical record number.
Morrison 1978	This study was included in original review. It is excluded from this update because of > 20% post‐randomisation exclusions and the fact that it was possibly quasi‐randomised.
Mulder 1997	This study compares the effects of betamethasone vs dexamethasone on antenatal fetal heart rate.
Papageorgiou 1979	This study was included in original review. It is excluded from this update because of > 20% post‐randomisation exclusions. Of 146 babies included in the study, the paper only reports outcomes for 61.
Romejko‐Wolniewicz 2013	This is a head‐to‐head trial of 2 different regimens and is eligible for the Cochrane review entitled 'Different corticosteroids and regimens for accelerating fetal lung maturation for women at risk of preterm birth' Brownfoot 2013.
Rotmensch 1999	This study compares the effects of betamethasone vs dexamethasone on antenatal fetal heart rate.
Schmidt 1984	This study was included in original review. It is excluded from this update because of > 20% post‐randomisation exclusions. The paper only reports results from 92 of 144 randomised mothers and 97 of 149 randomised babies.
Simpson 1985	Quasi‐randomised study. Randomised participants are combined with a non‐randomised cohort and cannot be analysed separately.
Whitt 1976	This trial compares IM betamethasone with IV cortisol. It does not meet our entry criteria for inclusion of studies for the review.

IM: intramuscular IV: intravenous PROM: premature rupture of membranes RDS: respiratory distress syndrome TRH: thyrotropin‐releasing hormone vs: versus