Neonatal infections are infections of the neonate (newborn) acquired during prenatal development or in the first four weeks of life (neonatal period). Neonatal infections may be contracted by mother to child transmission, in the birth canal during childbirth, or contracted after birth. Some neonatal infections are apparent soon after delivery, while others may develop in the postnatal period. Some neonatal infections such as HIV, hepatitis B, and malaria do not become apparent until much later.

There is a higher risk of infection for preterm or low birth weight neonates. Infant respiratory distress syndrome is often a condition of preterm neonates that can have long-term negative consequences, it can also arise following an infection. In some instances, neonatal respiratory tract diseases may increase the susceptibility to future respiratory infections and inflammatory responses related to lung disease.Antibiotics can be effective for neonatal infections, especially when the pathogen is quickly identified. Instead of relying solely on culturing techniques, pathogen identification has improved substantially with advancing technology; however, neonate mortality reduction has not kept pace and remains 20% to 50. While preterm neonates are at a particularly high risk, all neonates can develop infection. Neonatal infection may also be associated with premature rupture of membranes (breakage of the amniotic sac) which substantially increases the risk of neonatal sepsis by allowing passage for bacteria to enter the womb prior to the birth of the infant.Neonatal infection can be distressing to the family and it initiates concentrated effort to treat it by clinicians. Research to improve treatment of infections and prophylactic treatment of the mother to avoid infections of the infant is ongoing.