Objectives: To determine the occurrence of infantile colic and its seasonal variation in an unselected population and to evaluate the amounts of crying in colicky infants and noncolicky controls.
Design: Questionnaire survey and a prospective substudy of parental diaries of crying.
Setting: All families with a full-term, healthy-born infant in the Turku City (Finland) district during 1 year.
Participants: Colic was defined as paroxysms of crying for 3 or more hours per day for 3 days or more per week during a period of at least 3 weeks. The questionnaires containing this definition were distributed to 1221 families in postpartum wards, and an invitation to a prospective follow-up study was presented to the families if their infant showed colicky symptoms. The incidence questionnaire was to be returned after 3 months. Six hundred four (49%) of the questionnaires were returned, and an additional 355 (29%) families were reached by phone. A total of 59 families with a colicky infant enrolled in the prospective substudy when the infants were at a median age of 5 weeks; age-matched controls were invited from the same population.
Results: The incidence of infantile colic was 13%; possible infantile colic was 8%. No seasonal variation was found. The mean amount of total crying was 241 min/d (95% confidence interval [CI], 216 to 266 minutes) in the colic group and 112 min/d (95% CI, 95 to 130 minutes) in the control group during the first recording week. The mean amount of colicky crying was 122 min/d (95% CI, 102 to 142 minutes) in the colic group and 19 min/d (95% CI, 12 to 26 minutes) in the control group.
Conclusions: The incidence of colic was 13% with no seasonal variation. Parental perception of infantile colic correlated well with the amount of crying.