A growth spurt is a period when a child's height rapidly increases. Growth spurts are most obvious when a child is an infant (in the first year of life) and during the teen years (starting at about age 11 for girls and at about age 13 for boys).
The signs of a growth spurt include:
Growth spurts can last days to years.
During the first year of life, growth spurts typically occur during the following ages:
WebMD Medical Reference from Healthwise