Cribsheet: A Data-Driven Guide to Better, More Relaxed Parenting, from Birth to Preschool (The ParentData Book 2)

by Emily Oster

Based on this definition, colic is pretty rare. In one study of 3,300 babies, researchers found that at one month of age, 2.2 percent of babies fit the “rule of three” colic definition; this is similar at three months.