Objective To assess the health cost (or benefit) of crisis-driven migration by focusing on the infant mortality rate (IMR) of the Colombian diaspora in Venezuela and the Venezuelan diaspora in Colombia.

Methods We compare national to diaspora IMRs over the period 1980-2018. National IMRs are death-to-birth ratios reported by the official vital statistics, whereas diaspora IMRs are calculated by using a semiparametric regression model on the summary birth histories collected in the population censuses. We analyse the diaspora IMRs according to whether their arrival corresponds to precrisis or crisis-driven migration.

Results During crises, diaspora IMRs show better health outcomes than those of non-migrants. The Colombian diaspora had an average annual IMR of −1.8 (95% CI −3.3 to 0.28) per year and the Venezuelan diaspora had −4.5 (95% CI −5.8 to −3.3). However, the protective role of migration is neither guaranteed nor consistent, as a crisis in the country of destination exposes immigrants to worse health outcomes than the non-migrant population.

Conclusion Migration is a survival strategy that allows people to reduce the negative effects they face during a crisis in their country of origin. The distinction between crisis-driven and precrisis migration provides a framework for assessing the cross-border effects on health outcomes due to diaspora composition, particularly when populations face adverse conditions.