A neonatal nurse practitioner specializes in caring for infants, including premature babies and full-term babies who need to be in a neonatal intensive care unit, or NICU. A neonatal nurse practitioner, or NNP, is usually the leading medical professional providing care for a newborn. An NNP is an expert in infant conditions such as respiratory distress, low birth weight, premature birth, or other abnormalities or congenital diseases. In this career, you may work with a physician, and your responsibilities include assessing and monitoring patients and determining and carrying out treatment.