Who Counts as a Migrant? The Impact of Definitions on Mortality Estimates in Belgium
On June 24, 2025, the International Laboratory for Population and Health held a seminar titled: “Who Counts as a Migrant? Comparing Definitions and Their Impact on Mortality Estimates in Belgium.”
The presentation was delivered by Marina Vergeles, a PhD student at the Catholic University of Louvain (UCLouvain) and the Free University of Brussels (VUB), who shared findings from her dissertation research.
Significance
The study focused on how different definitions of a “migrant” (based on place of birth or citizenship) affect estimates of migrant population size and mortality in Belgium from 2016 to 2019. The topic is highly relevant, as the choice of definition significantly influences demographic indicators, which is critical in the context of Belgium’s diverse population and the need for accurate data to inform social and health policy.
Methodology and Data Sources
The analysis utilized data from Belgium’s National Register (DEMOBEL database), including information on population size, citizenship, place of birth, and mortality. Age- and sex-standardized mortality rates were applied to compare indicators across groups. The presenter highlighted data limitations, such as unregistered migrants, delays in registration, lack of education data, and incomplete information on origin. To address these issues, additional variables were requested from Belgium’s statistical office.
Key Findings
The study revealed that the size of the migrant population varies significantly depending on the definition used. For migrants from Turkey and African countries, where obtaining Belgian citizenship is more common, using citizenship as a criterion underestimates the migrant population compared to place of birth. Overall, migrant mortality rates were lower than those of the native population, except for the Turkish group. Mortality estimates for migrants of Turkish and North African origin based on citizenship were 10–20% higher than those based on place of birth, while for migrants from Western Europe and sub-Saharan Africa, citizenship-based estimates were 5–10% lower. These differences underscore the importance of the chosen definition when analyzing migrant subgroups.