There will be two aims. In the first aim, a prospective, randomized pilot study, will test the effects of pre-emptive postnatal antibiotics on the microbiome, metabolome and inflammatory responses in the neonate during the NICU course. The second aim will assess the effects of pre-emptive postnatal antibiotics on adverse outcomes in the neonate while in the NICU. The hypothesis is that higher antibiotic use will not be associated with decreased early onset sepsis and in fact, will be associated with increased adverse outcomes including retinopathy of prematurity, necrotizing enterocolitis, spontaneous ileal perforation, late onset sepsis, chronic lung disease, bronchopulmonary dysplasia, intraventricular hemorrhage, periventricular leukomalacia, and mortality.