"Smothered" Infants-Neglect, Infanticide or SIDS? A Fresh Look at the 19th Century Mortality Schedules

Based on the U.S. Federal Mortality Schedules from the years 1850-1880 infant deaths < 1 year were investigated in order to determine whether mortality attributed to "smothering" or "overlaying" followed known SIDS trajectories. By comparing a case sample of 2,236 smothered/overlaid deaths with an age-, regionally and time-matched control sample of all-cause infant deaths (N = 58,293), striking similarities with SIDS became apparent, which were not mimicked in the control sample. These epidemiological traits included a disproportionate vulnerability during the second to fourth month of life (Poisson RR 12.94, p < 0.001), a remarkable birth and death seasonality, as well as pronounced racial disparities. The study could also corroborate sex-specific discrepancies-such as differential impact of month of birth on age-at-death. Results of a Cox regression furthermore indicate that age, sex, race and death season were significant predictors of mortality. This strongly supports the hypothesis that these infant deaths represent empirical evidence of 19th century SIDS.