Child mortality in Stockholm during 1885-1910: the impact of household size and number of children in the family on the risk of death from measles.

Previous studies have associated overcrowding at the household level with increased mortality, especially from airborne diseases. This association may be confounded by associations with adverse socioeconomic conditions or low age at infection. This study investigated the effect of crowding on the risk of measles death. Individual entries in a population-based register and on death certificates for children aged 0-15 years living in one parish in Stockholm in 1885, 1891, and 1910 (n = 36,718) were used to analyze cause-specific and overall death rates in relation to household size and the number of children in the household, using Cox regression analysis. Bivariate analysis identified significant relations between crowding and the cause-specific risk of death, which were subsequently tested while controlling for other known risk factors for childhood death. Significant negative associations between crowding and the risk of death from pneumonia and bronchitis disappeared when controlling for other risk factors. A negative association between the risk of overall death and large household size became significantly positive when controlling for other risk factors. The increased risk of death from measles associated with proxies for crowding remained after controlling for other risk factors. In conclusion, crowding may have a statistically independent effect on the risk of death from measles.