Detroit 3 1996.

Methods	Randomised controlled trial.
Participants	610 women 24‐33 weeks' gestation who were expected to give birth within 24 hours.
Interventions	10 mg/kg intravenously phenobarbital (n = 309) then, 100 mg phenobarbital or placebo orally until delivery or > 32 weeks or placebo (n = 301).
Outcomes	Primary outcome: intracranial haemorrhage, (only ascertained for liveborn babies born at < 34 weeks (311 in intervention group and 279 in control group), or early death (< 72 hours). Secondary outcomes: maternal side effects, intracranial haemorrhage, periventricular leucomalacia, infant neurodevelopment. Outcomes of follow up at 18‐22 months (corrected age): physical growth, neurologic and developmental outcomes.
Notes	Approximately 60% antenatal corticosteroid usage in each group. Trial stopped after 610 women recruited (of a calculated sample size of 1038) as probability of showing a statistically significant treatment effect was unlikely.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Randomly assigned by a pharmacist.
Blinding? All outcomes	Low risk	Placebo used. Blinded primary outcome assessment.
Incomplete outcome data addressed? All outcomes	Low risk	35/309 (11%) women in the phenobarbital group and 40/301 (13%) women in the placebo group were excluded postrandomisation due to continuation of the pregnancy beyond 33 weeks and delivery prior to initiation of the treatment (12% excluded). Follow up at 18‐22 months excluded 118/344 (34%) infants in the phenobarbital group and 114/324 (35%) infants in the placebo group due to delivery after 34 weeks, death before and after discharge from the neonatal intensive care unit, and failure to attend the 18 to 22 month follow‐up visit (in total 232/668 (35%) infants at randomisation were excluded).
Free of selective reporting?	Low risk	No indication of selective reporting.
Free of other bias?	Low risk