Objective: To measure annual rates of infant injury death in Washington State and identify potential risk factors for infant injury death.
Methods: A population-based case-control study using a linked file of birth and death certificates for the years 1981 through 1990.
Results: The leading causes of infant injury death, per 100,000 live births, were intentional injury (9.1); suffocation, choking, or hanging (6.9); motor vehicle crashes (4.4); and drowning (3.2). Unintentional injury death rates fell steeply during the 1970s but remained steady during the 1980s. Infanticide rates rose during the 1980s. Young maternal age (odds ratio, 9.0; 95% confidence interval, 4.5 to 17.9, for age < 20 years vs age > 30 years) and higher parity (odds ratio, 5.0; 95% confidence interval, 3.1 to 8.3, for parity of two or more vs parity of zero) were associated with infant injury death. There was a twofold increase in the risk of infant injury death if the mother smoked, was black, or lived in a rural area. Male sex of the infant, late prenatal care, and low income were associated only with intentional deaths, while higher parity was more strongly associated with unintentional injury deaths.
Conclusions: During 1981 through 1990, infant mortality caused by injuries increased in Washington State. Young maternal age and higher parity were strongly associated with infant injury death.