An infant is considered to be a "newborn" or "neonate" up to age 1 month (4 weeks old). This "neonatal period" represents a short�time of life where changes are very rapid and when many critical events can occur.

During the first 30 days, most congenital defects (such as congenital heart disease) are discovered. Genetic abnormalities may show up and it is a time when infections such as congenital herpes, group B strep, toxoplasmosis and others are discovered as they begin to have�effects on the baby.