Robyn Nicole Donrovich

Early life conditions, partnership histories, and mortality risk for Swedish men and women born 1915–1929

This paper investigates the relationship between early life biological and social factors, partnership history, and mortality risk. Mortality risks for Swedish men and women over age 50 in the Uppsala Birth Cohort born 1915-1929 were estimated using survival analysis. Relative mortality risk was evaluated through nested multiplicative Gompertz models for 4348 men and 3331 women, followed from age 50 to the end of 2010. Being born to an unmarried mother was associated with higher mortality risk in later life for men and women, and relative to married individuals, being unmarried after age 50 was associated with elevated mortality risk. Single women and divorced men were the highest risk groups, and women were negatively impacted by a previous divorce or widowhood, while men were not. Both genders showed direct effects of early life variables on later life mortality and were vulnerable if unmarried in later life. However, in this study, previous marital disruptions appeared to have more (negative) meaning in the long-term for women.

Salmon Bias or Red Herring

The purpose of this research is to empirically test the salmon bias hypothesis, which states that the “healthy migrant” effect—referring to a situation in which migrants enjoy lower mortality risks than natives—is caused by selective return-migration of the weak, sick, and elderly. Using a unique longitudinal micro-level database—the Historical Sample of the Netherlands—we tracked the life courses of internal migrants after they had left the city of Rotterdam, which allowed us to compare mortality risks of stayers, returnees, and movers using survival analysis for the study group as a whole, and also for men and women separately. Although migrants who stayed in the receiving society had significantly higher mortality risks than natives, no significant difference was found for migrants who returned to their municipality of birth (returnees). By contrast, migrants who left for another destination (movers) had much lower mortality risks than natives. Natives who left Rotterdam also had significantly lower mortality risks than natives who stayed in Rotterdam. Female migrants, in particular, who stayed in the receiving urban society paid a long-term health price. In the case of Rotterdam, the salmon bias hypothesis can be rejected because the lower mortality effect among migrants was not caused by selective return-migration. The healthy migrant effect is real and due to a positive selection effect: Healthier people are more likely to migrate.