Participants will be assigned to one of two groups: women taking methadone who will breastfeed their babies or women taking methadone who will bottle-feed their babies. On Days 1, 2, 3, 4, 14, and 30, following infant delivery, plasma will be collected from both groups and breast milk will be collected from the breastfeeding group. These samples will be quantitatively analyzed for methadone. Infants will undergo neurobehavioral assessments on Days 3, 14, and 30, following birth. Rates and severity of neonatal abstinence syndrome will also be evaluated.