In a 1999 landmark trial, Tyson et al (N Engl J Med 1999;340:1962-8. https://doi.org/10.1056/NEJM199906243402505) reported that 4 weeks of intramuscular vitamin A reduced deficiency and modestly bronchopulmonary dysplasia (BPD) or death in preterm infants <1000 grams (relative risk, 0.89). However, clinical practice, the use remains variable, large part because concerns about pain injections al...