Neonatal infections are infections of the neonate (newborn) during the neonatal period or first four weeks after birth. Neonatal infections may be contracted by transplacental transfer in utero, in the birth canal during delivery (perinatal), or by other means after birth. Some neonatal infections are apparent soon after delivery, while others may develop postpartum within the first week or month. Some infections acquired in the neonatal period do not become apparent until much later such as HIV, hepatitis B and malaria.