Ruth 1991.

Methods	Single‐center randomized controlled trial in Finland
Participants	Included 38 term infants with evidence of perinatal asphyxia (5‐minute Apgar score ≤ 3 or need for mechanical ventilation > 30 minutes after birth)
Interventions	Phenobarbital group (n = 21) received conventional therapy plus a phenobarbital loading dose (30 mg/kg IV) prior to 4 hours of age, followed by a second dose of phenobarbital (15 mg/kg) 4 hours after the initial dose. These infants then received 5 mg/kg/day for 5 days Control group (n = 17) received conventional therapy
Outcomes	Death before neurodevelopmental assessment Severe neurodevelopmental disability (stated as cerebral palsy) 6‐year neurodevelopmental outcome (assessed using WISC‐r expressed as IQ; neuropsychological tests (VMI, NEPSY) and quality of life scale)
Notes	Co‐intervention: not stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of randomization was not specified
Allocation concealment (selection bias)	Unclear risk	Allocation concealment was not specified
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Blinding of the treatment team and assessors was not specified
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	6‐year follow‐up: unclear how many infants were included, means presented for "testable infants"
Selective reporting (reporting bias)	Low risk	All outcomes were reported