The purpose of this study is to determine the pharmacokinetics (PK) of montelukast (Singulair) in very low birth weight (VLBW) infants at risk for developing bronchopulmonary dysplasia (the need for supplemental oxygen). The investigators' long-term hypothesis is that inhibition of leukotriene signaling in the VLBW preterm lung will decrease inflammation, remodeling and the incidence of bronchopulmonary dysplasia (BPD).