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Gender differences in rates of unintentional head injury in the first 3 months of life.

OBJECTIVES
To assess for gender differences in rates of unintentional head injury in infants less than 3 months of age, to assess the circumstances of injury in these patients, and to look for gender-related differences in these circumstances.


METHODS
Two separate databases were analyzed. 1) The National Pediatric Trauma Registry (NPTR) was queried for all patients < or = 90 days of age who had been diagnosed with unintentional head trauma between 1990 and 1999. The proportion of males was compared to the expected proportion of 51%, derived from US census data. 2) A prospective cohort of 88 infants < or = 90 days of age who had been treated for unintentional head trauma in an urban pediatric emergency department (ED) was studied. Circumstances of injury and gender-related differences in these circumstances were assessed.


RESULTS
In the NPTR database, 600 of 1072 (56%) (95% confidence interval [CI] 0.53, 0.59) infants < or = 90 days of age were boys (P =.001). In the ED cohort, 54 of 88 (62%) (95% CI 0.50, 0.72) subjects were boys (P =.06). In virtually all of the cases described, subjects appeared to be passive participants in the injury. The most commonly reported circumstances of injury were the following: "child left alone on furniture and fell" (n = 39) or "parent dropped child" (n = 27). Boys accounted for 20 (74%) of the subjects in the "parent dropped child" group (P =.04).


CONCLUSIONS
Boys outnumber girls among infants less than 3 months of age with unintentional head trauma. These young infants appear to be passive participants in their injuries, which indicates that differences in parenting practices may account for the observed gender differences.