Neonatal pneumonia is the infection of the lung tissue (also called the lower respiratory tract) of the newborn. That is, of a baby less than one-month-old. Although in practice it usually refers to a child less than 7 days old. This infection can be caused by different microorganisms (viruses and bacteria), although bacterial infection
is more frequent. The infection can occur within the mother's womb or after the baby has already been born.