 Bronchopulmonary dysplasia BPD, also known as chronic lung disease CLD, is a major complication of premature birth and is associated with a significant increased risk of complications including death. Diuretics have been used for decades in babies with BPD and are considered a standard of care. Patients receive electrolyte supplementation to replace the electrolytes removed by the diuretics. Spironolactone is not as good as other diuretics at removing extra fluid, but it is different from chlorothiazide and furosemide because instead of removing potassium, it actually can increase potassium levels in our body. Spironolactone is used with chlorothiazide to try to minimize the potassium lost; therefore, reduce the electrolyte supplementation needed. However, studies have suggested that preterm babies aren t developed enough to appropriately respond to spironolactone. Also, one study has shown that adding spironolactone to chlorothiazide in patients with BPD has no effect on whether or not patients receive electrolyte supplementation. This study will examine whether there is a difference in the amount of electrolyte supplementation between patients receiving chlorothiazide only or chlorothiazide plus spironolactone. the investigators hypothesize there will be no difference in the amount of electrolyte supplementation between the two groups. 