State-by-state causes of infant mortality in the US
Sudden unexpected death of infants (SUDI) was the most common cause of infant mortality among children born full term in the U.S. according to estimates from a state-by-state study published this week in PLOS Medicine. The study, conducted by Neha Bairoliya of Harvard University and Gunther Fink of the Swiss Tropical and Public Health Institute, found that very low rates of SUDI—which includes sudden infant death syndrome (SIDS), accidental or abuse-related death, and sudden death from ill-defined causes—have been achieved in a few states while rates remain high in most others. The results suggest potential for a major reduction in infant mortality through interventions to reduce SUDI risk.
In their study, Bairoliya and Fink used linked birth and death records to identify the state- and cause-specific burden of infant mortality among full-term infants (born at 37-42 weeks of gestation). A total of 10,175,481 infants born full-term in the US between January 1, 2010, and December 31, 2012, were analyzed. Full-term infant mortality rate (FTIMR) was 2.2 per 1,000 live births overall, and ranged between 1.29 (Connecticut, 95% confidence interval 1.08, 1.53) and 3.77 (Mississippi, 95% CI 3.39, 4.19) at the state level. SUDI accounted for 43% of FTIM; congenital malformations and perinatal conditions accounted for 31% and 11.3% of FTIM, respectively. The largest mortality differentials between states with good and states with poor FTIMR were found for SUDI, with particularly large risk differentials for deaths due to sudden infant death syndrome (SIDS) (odds ratio [OR] 2.52, 95% CI 1.86, 3.42) and suffocation (OR 4.40, 95% CI 3.71, 5.21).
The extent to which these state differentials are due to antenatal care standards, access to health services, or postnatal practices could not be determined. However, after adjustment for differences in maternal education, race, and maternal health, substantial state-level variation in in SUDI remained (OR 1.70, 95% CI 1.48, 1.94). Bairoliya and Fink project a reduction in full-term infant mortality of 4,003 deaths (95% CI 2,284, 5,587) annually in the U.S. if all states were to achieve the mortality levels of the best-performing state in each cause-of-death category. The authors state, "[g]iven the high mortality burden due to SIDS and suffocation, policy efforts to promote compliance with recommended sleeping arrangements could be an effective first step in this direction."