Epo also did not affect inflammatory markers in the PENUT trial, despite data in rodents that this was one of the mechanisms of action.129 Potential reasons why Epo was ineffective include important differences between preterm infants and preclinical models, incorrect timing of the intervention, incorrect dosing schedule or the possibility that iron deficiency in the Epo-treated group contributed to the lack of benefit in children enrolled in the PENUT Trial. Here, EPO is linked to Iron deficiency anemia.