Population Change and Lifecourse

Research Brief #16 - September 2013

The Effects of Age and Background on the Fertility Patterns of Child Migrants


This paper challenges the common notion that immigrants have more children than the native-born population. More specifically, immigrants who arrived in Canada, England or France at an early age have about the same number of children as the native-born. By examining child immigrants, the paper is able to attribute this finding to the hypothesis that, with time, immigrants adopt the destination country’s norms. The results also show that the relationship between age at migration and number of children differs for immigrants from certain countries. Likewise, the fertility patterns of child migrants also depend on their destination country.

Key Findings


Since many OECD countries have experienced a dramatic increase in the share and diversity of their foreign-born population, a large body of research has been devoted to understanding the contributions that immigrants can make. More specifically, much attention has been devoted to examine the extent to which the fertility of the foreign-born population differs from that of the native-born. However, most studies have focused on the fertility of adult immigrants, which may be shaped by “selection”, “disruption” or “adaptation” (Goldstein and Goldstein 1981). The selection hypothesis suggests that people who migrate choose countries that are similar to them and thus they may have similar fertility patterns even before they arrive (Forste and Tienda 1996; Kahn 1988; Sobotka 2008). The disruption hypothesis suggests that people prefer to postpone childbearing until they have migrated and have settled, causing a decrease in fertility before the migration followed by an increase after arrival (Ng and Nault 1997; Toulemon 2004). Finally, the adaptation hypothesis suggests that as migrants settle in the destination country, their fertility patterns become more similar to those of the native-born population. However, by examining child migrants we can better understand the adaption process since selection and disruption play less of a role in this demographic.

Method and Data

The dependent variable was fertility (number of children), which was defined using the “own child” method (number of children living in the household), in women under 45 years of age in Canada, England, and France. Women who migrated at the age of 18 or younger were defined as “child migrants”. The data was analyzed using four sets of models. The first set estimates average differences in fertility between child immigrants and the native born. The second set accounts for the place of origin of the child migrants. The third set examines whether children who migrated at an earlier age show fertility patterns more similar to those of the native population. Finally, the question of whether the relationship between age at migration and fertility varies by place of origin is examined. Control variables included census year, age, region of residence, marital status, education, and socioeconomic and demographic factors.

For Canada, the data was drawn from the Canadian Census of Population for the years 1991, 1996, 2001 and 2006. For England, the data was drawn from the Office for National Statistics Longitudinal Study (1991 and 2001) and census records (1971 to 2001) together with administrative records. For France, the data was drawn from the Enquête sur Trajectoires et Origines (2008).


Figure 1. Incidence Rate Rations for Fertility, by Age at Immigration in England and Wales, France and CanadaIn all three countries, women who migrated when they were children generally have more children than their native-born counterparts. In Canada, the fertility rate among child-immigrant women is 8% higher than for Canadian-born women, and the effect is even more pronounced for France and England. In addition, fertility increased with age at migration and the younger the child immigrant, the more similar their fertility rates were to that of the native-born population. For example, children who migrated to Canada before the age of six have fertility rates that are very similar to that of the Canadian-born. However, this fertility differential increased to about 4% if they arrived between the ages of 6 and 11, 10% if they arrived between the ages of 12 and 15, 22% if they arrived at age 16, and 32% if they arrived at age 18. As Figure 1 shows, these results are stronger in England and France than in Canada.

However, there were marked differences by country of origin. For women from geographic areas with similar language and culture as the destination country, fertility rates were very similar, whereas marked differences were observed for women from geographical regions with dissimilar language and culture. For example, women born in the US who later migrated as children to Canada display very similar fertility patterns as Canadian-born women (see Figure 2). But women who migrated as children from Mexico, Central America and the Middle East display much higher fertility rates, and those from Europe (except for Southern Europe) and Asia (except from Southern Asia) display much lower fertility rates compared to Canadian-born women. In addition, children from Asia and the Pacific that migrated to England have fertility rates that are very similar to those of the English-born at all ages of migration. This is in contrast to migrants from South America, who have many more children than the English-born if they arrived between the ages of 6 and 16.Figure 2. Incidence Rate Ratios for Fertility, by Age at Immigration and Place of Birth Relative to the Native-Born in Canada


This paper examined the extent to which the fertility rates of immigrants who arrived as children to one of three OECD countries (Canada, England and Wales, and France) differed from that of the native-born. By studying child migrants who were exposed to the destination country’s norms very early in life, the paper is able to explore the adaptation process that shapes their fertility. The paper has important implications with respect to the demographic contribution that immigrants can make. First, the common notion that immigrants have more children than the native born is challenged by these findings since very young child migrants tend to have fertility rates that are very similar to those of the native-born population. Second, one must be aware of the make-up of the foreign-born population since they are an extremely diverse group. Finally, one must also be attentive to the social and institutional diversity among destination countries to better predict immigrants’ adaptation to fertility norms. A failure to account for these factors makes it difficult to understand the contribution immigrants bring to the demographic sustainability of their destination countries.


About the Study

The research brief is based on: Alícia Adserà, Ana M. Ferrer, Wendy Sigle-Rushton, and Ben Wilson. 2012. Fertility Patterns of Child Migrants: Age at Migration and Ancestry in Comparative Perspective. The ANNALS of the American Academy of Political Science and Social Science 643:160-239. The brief was written by Danniel Varona-Marin.

For more information, please contact Ana Ferrer.