The American Academy of Pediatrics reports that colic is a common ailment in infants that typically develops between the second and fourth weeks of life.
Symptoms include inconsolable crying – particularly in the early evening; the infant extending or pulling up her legs; and wind. Some infants’ stomachs may even appear enlarged or distended with wind. While there is no clear explanation for its cause, it is often attributed to an immature nervous system, and the condition will likely improve as baby grows.

It is important for parents who believe that their infant is suffering from colic to consult their pediatrician and make sure that the crying is not related to any serious medical condition.