Age in months and birth order in infant nonfatal injuries: A retrospective cohort study

Objective: To examine the age in months at which infants visited outpatient clinics or emergency rooms for the first time for nonfatal injuries and to identify risk factors for the occurrence of these injuries. Study design: Retrospective cohort study. Methods: We used a health insurance claims database in Japan. Infants born between April 2012 and December 2014 were identified and followed until 12 months of age. We identified their first visit to outpatient clinics or emergency rooms because of nonfatal injuries (wounds/fractures, foreign bodies, and burns). Cox regression analysis was used to examine the association of nonfatal injuries with infants’ sex, birth order, and parental age. Results: We identified 46,431 eligible infants. Of these, 7606 (16.4%) were brought to an outpatient clinic or emergency room for nonfatal injuries within 12 months of birth. Of the 7,606, 21.7% were aged ≤4 months and 44.7% ​≤ ​7 months. First-born infants were more likely to have wounds/fractures and burns. Conclusion: One-fifth of first nonfatal infant injuries occurred within 4 months of age. Healthcare providers should provide early education about injury prevention, especially to caregivers of first-born infants.