Sudden unexpected infant deaths in Dundee, 1882-1891: overlying or SIDS?

Using a cohort study of all deaths in infants under 12 months in Dundee born between 1882-91 we set out to compare the aetiology of sudden unexpected infant deaths in Dundee at the end of the 19th Century with the aetiology of present day Sudden Infant Death Syndrome (SIDS). During 1882-1891, 361 infants died suddenly and unexpectedly and without obvious cause while in bed with their parents. The sex ratio of deaths was even (0.51 male) whereas the typical male fraction of SIDS today is 0.61. The mean age at death was almost two and one-half weeks younger in the Dundee cohort than for SIDS in modern Scotland. The infants in the Dundee cohort were discovered more frequently early in the morning than is typical. Their social class distribution was different in that no overlying cases were found in the higher classes whereas SIDS affects all classes. The overlying rate for illegitimate infants was lower than that reported for SIDS today. The epidemiological characteristics of the Dundee cohort and of those dying from present day SIDS differ considerably. The Dundee cohort apparently died from overlying rather than from SIDS as it is classified today. Present day advice that co-sleeping is safe should be given more cautiously until the safety of co-sleeping is resolved. It might be prudent to inform parents that co-sleeping is a risk factor for SIDS and that it should therefore be avoided.