Metformin for Premature Infants With Bronchopulmonary Dysplasia

The overall objective of this study is to investigate the role of metformin in decreasing lung injury and promoting lung growth in premature infants. There are two phases to this pilot study. For Phase 0, the goal is to investigate the safety and tolerance of oral metformin in premature who have been diagnosed with bronchopulmonary dysplasia (BPD) at 36-44 weeks gestation. For Phase 1, the goal is to investigate metformin safety and tolerance in extremely premature infants who are 7-30 days old who have an increased risk of BPD. The main questions it aims to answer are: * how well do older premature infants tolerate metformin? * how well do younger premature infants tolerate metformin?