Early-life risk factors for both infant colic and excessive crying without colic

Infantile colic may represent gastrointestinal distress, yet most definitions emphasize excessive crying. Each may have distinct etiologies.

In a pre-birth cohort, we used maternal reports of infant crying and apparent abdominal discomfort at 6mos to categorize infants as (1) unaffected (no excessive crying or colic), (2) excessive crying only, and (3) colic (abdominal discomfort +/- excessive crying). We examined associations of potential risk factors in separate models with excessive crying and colic (each vs. unaffected) using unadjusted multinomial logistic regression, and associations between count of risk factors and colic using logistic regression.

Of 1403 infants, 140 (10%) had excessive crying, and 346 (25%) colic. Infants that were non-Hispanic white, low birthweight, firstborn, or had a maternal history of atopy, high postpartum depressive symptoms, or persistent prenatal nausea, had a 40-80% higher relative risk of colic. Preterm birth was associated with double the risk. Being firstborn, low birthweight, and preterm birth predicted excessive crying. Infants with ≥four (vs. 0-1) of the seven identified risk factors had 3.9 times (95% CI: 2.6, 6.1) higher odds of colic.

Colic characterized by apparent abdominal discomfort can be phenotypically distinguished from excessive crying only. Multiple risk factors may further increase colic risk.

Infant colic characterized by apparent gastrointestinal distress may be phenotypically distinct from excessive crying only. Literature that defines colic only based on crying behaviors may miss important predictors. Mother-reported colic and excessive crying appear to have overlapping risk factors, with additional risk factors identified for colic. The presence of multiple risk factors increases the risk of colic, supporting a multifactorial etiology.