A number of studies have shown that immigrants tend to be in better health than their fellow citizens in their host countries, at least during the initial period following their arrival. Our work, a systematic review which brings together the results of 77 empirical research studies on this question, demonstrates that while the “healthy immigrant” effect is usually found in adult immigrants, it is another matter for children and older people. The extent of the healthy immigrant selection effect is also much more significant in terms of mortality than of morbidity. Our analysis suggests that immigrant health policies should not be “one size fits all” in type, but need to take into account both the age of immigrants and also those particular health indicators in terms of which the immigrants are most vulnerable.
We analysed research published in either French or English between 1980 and 2014 in journals of social science, behavioural sciences, medicine, public health and social work. The search engines used were PubMed, Medline, Global Health, SOC Index, JSTOR and Clinical Key, using the key words “healthy immigrant effect”, “migrant health”, and “immigration and health”. The database totalled 1,135 articles and reports. Of these, 200 were studies carried out in Canada, or included Canada as part of an international analysis. We also identified and found publications considered to be relevant which were cited in the Canadian publications. In total our review is based on 77 studies.
With 6.7 million immigrants in Canada, and projected increases of an additional 334,000 foreign-born residents per annum by 2035/2036 (Statistics Canada, 2014 ), the health of immigrants and their descendants could have important implications for the future of the Canadian health system. Many studies have shown that adult immigrants are generally in better health than the population born in the host country, at least for the first years after arrival. They also tend to be in better health than non-migrants in their countries of origin. This phenomenon has been observed in Europe , the United States and Canada. Although there have been several studies of the health of immigrants to Canada, few studies have attempted a systematic review of the question which looks more closely at immigrants’ ages and their life-courses. Our report is designed to fill this gap.
The Canadian points system selects immigrants on the basis of human capital, and favours individuals who speak a host country language and have a high level of education, a solid basis of work experience, and other skills which may contribute to success in the post-migration jobs market. These characteristics are also correlated with better health. In addition, Canada requires candidates for immigration to undergo a medical examination, in order to minimise the costs of health care and the risks to public health.
On the individual level, the process of migration tends to favour the movement of people who are in good health and who are capable of planning and coping with their journey. Migrants thus tend to possess the personal characteristics which may be associated with better than average health.
On the other hand, immigrants coming from countries with low-calorie dietary regimes may have more difficulty in adapting to environments which are rich in calories. Obesity is a threat to immigrants who are not able to cope with the high-carbohydrate foods of North America.
Our review shows that the health of immigrants varies with the length of their stay in their host country. We also find differences between sub-groups (adults, children, older people) within the immigrant population.
The perinatal period
Immigrant mothers rate their own health as less good than mothers born in Canada. They also have more frequent health problems, for example those linked to the post-partum period (such as pain, bleeding, high blood pressure, infections and poor health in general) than their compatriots born in Canada.
Immigrant women are more likely to have small for gestational age babies than Canadian-born women. However, it is difficult to know whether there is a real health deficit involved in the higher proportion of such births among immigrant women, when we consider that the way in which such births are identified may vary depending on the birth weight reference curve being used.
Childhood and adolescence
Multiple variations in the health of children of immigrants, as measured in different ways, mean that we are unable to state whether they are in better or worse health than children born in Canada. The same is true of adolescents. Studies of the weight of children and young people, measured using the body mass index, have produced only mixed results.
As a general rule, adult immigrants tend to score more positively than adults born in Canada in terms of mental health, functional limitations and disabilities, risky behaviours, and chronic diseases. By contrast, results for self-rated health is more heterogeneous and vary more widely depending on immigrants’ country of origin and length of stay in Canada.
The health of older immigrants is generally similar to that of their compatriots born in Canada. Older immigrants and older people born in Canada have similar risks of chronic diseases and mental illness. Self-rated health shows divergences related to immigrant life courses, length of stay in Canada, and also between men and women.
There is little research on the health of refugees, but the studies we have consulted show that refugees and their children tend to have poorer health than the population born in Canada. For example, refugee mothers who give birth in Montréal, Toronto and Vancouver have a risk of post-partum depression which is five times higher than mothers born in Canada. Four months after giving birth, they also have more frequent pain, bleeding, high blood pressure, infections and problems of psychosocial health in general. In the same way, infant health problems are more frequent among babies born to refugees.
The healthy immigrant effect is very pronounced for mortality. Most studies have found lower mortality among immigrants compared with native-born Canadians, both in terms of general mortality and cause-specific mortality.
Current explanations of the healthy immigrant effect tend to focus on selection, acculturation and other exposures to harmful environments following migration. The last two factors are often measured using duration of residence in the host country, based on the hypothesis that longer term immigrants become more acculturated and have been more exposed to harmful post-migration environments than recent arrivals. Other determinants of the health of immigrants (for example, social support, socio-economic status and the characteristics of the area of residence) have also been researched.
Our analysis highlights some gaps which need to be studied in future research if we want to better understand the healthy immigrant effect in Canada. First, the studies we have reviewed do not take pre-migration experiences into account. For example, exposure to famine or to early childhood diseases in the country of origin may have effects on the health of immigrants even after their move to a new country. To our knowledge, none of the current nationally representative surveys used to evaluate the health of immigrants to Canada contains information on premigration experiences and conditions. Second, longitudinal analyses which follow individuals over time must be employed in future research in order to illuminate patterns and processes of health deterioration or convergence.
Canada’s immigration admissions policy selects for people in good health. Considering the close links between human capital and health, we would have expected to see a clear advantage in health for immigrants compared with Canadian residents born in Canada. Instead we found a much more complex model. The main trends were heterogeneous, showing a marked health advantage for adult immigrants, but less so for morbidity in early childhood, childhood and adolescence, and the later stages of life. The healthy immigrant effect is presented in the literature as an uncontestable fact, but our approach has enabled us to show that it is, in important ways, much more nuanced.
This policy brief is based on Zoua M. Vang, Jennifer Sigouin, Astrid Flenon, and Alain Gagnon (2015) The Healthy Immigrant Effect in Canada: A Systematic Review, a research synthesis prepared for the Population Change and Lifecourse Cluster, and published as PCLC Discussion Paper 3(1):4.
This policy brief was prepared by the authors of the paper.