Exploring familial factors in the migrant mortality advantage among domestic migrants in later life: Zeeland, the Netherlands, 1812-1962.

Many historical and contemporary studies have shown that migrants enjoy survival advantages over non-migrants, even if they originate from higher mortality regimes and have a lower socio-economic and educational status compared to non-migrants in the destination area. This so-called migrant mortality advantage or healthy migrant effect is explained in various ways. One of the main explanations refers to selection effects in the area of origin in the sense that healthier individuals are more likely to move compared to less healthy individuals. So far life-course analysis on the healthy migrant effect were focused on the survival chances of individual migrants compared to non-migrants. However, kin members of migrants might also enjoy survival advantages, given that health and mortality are often clustered in families due to shared environments, behaviors, resources, and household dynamics. We study whether kin members of migrants within the Dutch province of Zeeland also enjoy survival advantages. Although we find a mortality advantage for the migrating men and women in our sample, we find no mortality advantage for their siblings or offspring. However, there was a gendered effect of familial migration in the sense that women, contrary to men, had higher mortality risks if their siblings and parents migrated.

Effects of Individual Mortality Experience on Out-of-Wedlock Fertility in Eighteenth- and Nineteenth-Century Krummhörn, Germany.

Life history theory predicts that exposure to high mortality in early childhood leads to faster and riskier reproductive strategies. Individuals who grew up in a high mortality regime will not overly wait until they find a suitable partner and form a stable union because premature death would prevent them from reproducing. Cox proportional hazard models were used to determine whether women who experienced sibling death during early childhood (0-5 years) reproduced earlier and were at an increased risk of giving birth to an illegitimate child, with illegitimacy serving as a proxy for risky sexual behavior. Furthermore, we investigate whether giving birth out of wedlock is influenced by individual mortality experience or by more promiscuous sexual behavior that is clustered in certain families. Models are fitted on pedigree data from the eighteenth- and nineteenth-century Krummhörn population in Germany. The results show a relationship between sibling death in early childhood and the risk of reproducing out of wedlock, and reproductive timing. The risk of giving birth out of wedlock is linked to individual mortality experience rather than to family-level effects. In contrast, adjustments in connubial reproductive timing are influenced more by family-level effects than by individual mortality experience.

Salmon Bias or Red Herring? : Comparing Adult Mortality Risks (Ages 30-90) between Natives and Internal Migrants: Stayers, Returnees and Movers in Rotterdam, the Netherlands, 1850-1940.

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.