Although the magnitude of migration flows has been relatively stable over the past 20 years, the stock of international migrants has increased to over 230 million . These changes in migration patterns are the result of many factors including countries’ size, economic production, and demographic composition. Previous research on migration determinants has focused on migration to one or a handful of destinations or has used net migration to examine determinants. In this paper, I will use a harmonized global database of international migration flows to investigate the determinants of migration with special focus on the relationship of fertility in sending and receiving countries, which has not previously been studied as a driver of migration.
Data on migration flows between countries is merged with macroeconomic, geographic, and other country characteristics. An expanded gravity model is used to examine the determinants of migration flows between origin and destination, similar to previous research but with a focus on the role of total fertility rate (TFR) .
Almost half the migration flows between countries occur from high fertility countries to low fertility countries. When controlling for geographic and macroeconomic factors, high fertility rates in sending countries increase migration, but at very high levels of TFR migration rates begin to decrease. With controls, the relationship between TFR and destination is curvilinear; at low levels of TFR the rate of migration is lower, but as TFR in destination increases migration rate increases. While the absolute levels of TFR are significantly associated with migration rate, the relative fertility also impacts the migration rate between countries. The migration rate is significantly larger between those countries where the flow goes from a high TFR country to a low TFR country than in any other direction.
The fertility rate in both sending and destination countries appears to have an independent effect on migration flow. High fertility in sending countries generally increases migration, and high fertility in receiving countries is also associated with increased migration. One factor driving this finding is that although migration flows go to countries with high TFR, migrants are still migrating to countries that have a lower TFR than their origin country. When we look at migration rate by the difference in fertility rates, we see that the migration rate is highest between high fertility sending countries and low fertility destination countries. Migration destinations are more varied than previously, and many emerging economies are attracting immigrants although they have yet to complete the second demographic transition. This indicates that some of the impact of fertility on migration may be relative fertility and not just the absolute fertility of origin and destination countries.
 Abel GJ, Sander N (2-14). Quantifying global international migration flows. Science 343, 1520–1522.
 Kim K, Cohen JE (2010). Determinants of international migration flows to and from industrialized countries: A panel data approach beyond Gravity. Int. Migr. Rev. 44, 899–932.
Vegard Skirbekk and Marcin Stonawski, World Population, IIASA
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Last edited: 29 September 2015
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