Morales 1988.

Methods	Randomised clinical trial. All women received betamethasone.
Participants	92 women at less than 33 weeks' gestation. Not eligible if intrauterine growth restriction, known congenital abnormalities, or maternal bleeding disorder.
Interventions	10 mg vitamin K intramuscularly every 5 days until delivery (n = 46). Control group (n = 46) given no treatment.
Outcomes	IVH assessed by cranial ultrasound 24 and 72 hours after birth reviewed by a radiologist blinded to treatment. Other neonatal morbidity including respiratory distress syndrome. Cord blood clotting profiles.
Notes	No sample size estimation reported. All babies with any respiratory distress syndrome received mechanical ventilation.
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	Not reported by authors.
Allocation concealment?	Unclear risk	Allocation by sealed envelopes. Not reported if the envelopes were sequentially numbered or opaque.
Blinding? All outcomes	High risk	No placebo used, however, assessment of the primary outcome was blinded.
Incomplete outcome data addressed? All outcomes	Unclear risk	Losses to follow up not reported.
Free of selective reporting?	Low risk	No indication of selective reporting.
Free of other bias?	Unclear risk	Unclear.