Migration and Health

By Sandro Galea and Muhammad H. Zaman

A new introduction to a timeless dynamic: how the movement of humans affects health everywhere.

International migrants compose more than three percent of the world’s population, and internal migrants—those migrating within countries—are more than triple that number. Population migration has long been, and remains today, one of the central demographic shifts shaping the world around us. The world’s history—and its health—is shaped and colored by stories of migration patterns, the policies and political events that drive these movements, and narratives of individual migrants. 

Migration and Health offers the most expansive framework to date for understanding and reckoning with human migration’s implications for public health and its determinants. It interrogates this complex relationship by considering not only the welfare of migrants, but also that of the source, destination, and ensuing-generation populations. The result is an elevated, interdisciplinary resource for understanding what is known—and the considerable territory of what is not known—at an intersection that promises to grow in importance and influence as the century unfolds.

• Language: English
• Publisher: University of Chicago Press
• Release date: Nov 25, 2022
• ISBN: 9780226822495

Book preview

Cover Page for Migration and Health

Migration and Health

Migration and Health

EDITED BY SANDRO GALEA, CATHERINE K. ETTMAN, AND MUHAMMAD H. ZAMAN

THE UNIVERSITY OF CHICAGO PRESS

CHICAGO AND LONDON

The University of Chicago Press, Chicago 60637

The University of Chicago Press, Ltd., London

© 2022 by The University of Chicago

All rights reserved. No part of this book may be used or reproduced in any manner whatsoever without written permission, except in the case of brief quotations in critical articles and reviews. For more information, contact the University of Chicago Press, 1427 E. 60th St., Chicago, IL 60637.

Published 2022

Printed in the United States of America

31 30 29 28 27 26 25 24 23 22     1 2 3 4 5

ISBN-13: 978-0-226-82248-8 (cloth)

ISBN-13: 978-0-226-82250-1 (paper)

ISBN-13: 978-0-226-82249-5 (e-book)

DOI: https://doi.org/10.7208/chicago/9780226822495.001.0001

Library of Congress Cataloging-in-Publication Data

Names: Galea, Sandro, editor. | Ettman, Catherine K., editor. | Zaman, Muhammad H. (Muhammad Hamid), editor.

Title: Migration and health / edited by Sandro Galea, Catherine K. Ettman, and Muhammad H. Zaman.

Description: Chicago ; London : The University of Chicago Press, 2022. | Includes bibliographical references and index.

Identifiers: LCCN 2022015149 | ISBN 9780226822488 (cloth) | ISBN 9780226822501 (paperback) | ISBN 9780226822495 (e-book)

Subjects: LCSH: Emigration and immigration—Health aspects. | Immigrants—Health and hygiene. | Immigrants—Medical care.

Classification: LCC RA408.M5 M524 2022 | DDC 362.1086/912—dc23/eng/20220502

LC record available at https://lccn.loc.gov/2022015149

This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper).

Contents

PART 1. Why Migration and Health?

CHAPTER 1. An Introduction to Migration and Health

Sandro Galea, Catherine K. Ettman, and Muhammad H. Zaman

CHAPTER 2. Understanding Migration and Health: Social-Ecological and Lifecourse Perspectives

Catherine K. Ettman, Muhammad H. Zaman, and Sandro Galea

CHAPTER 3. The Global Drivers of Migration

Francesco Castelli

PART II. How Migration Affects Population Health

CHAPTER 4. Health of People Before Migration, the Healthy Migrant

Yudit Namer and Oliver Razum

CHAPTER 5. Health and the Process of Migration

Santino Severoni, Richard Alderslade, and Palmira Immordino

CHAPTER 6. Migration and Access to Health Care: Barriers and Solutions

Marie Norredam and Allan Krasnik

PART III. Topics in Migration and Health

CHAPTER 7. Climate Change, Migration, and Population Health

James M. Shultz and Andreas Rechkemmer

CHAPTER 8. Global Governance and the Health of Migrants

Agis D. Tsouros

CHAPTER 9. Migration and Changing Global Patterns of Infectious Diseases

Nicolas Vignier

CHAPTER 10. Mental Illness and Substance Use and Migration: Traumatic Exposures during High-Risk Migration

Sergio Aguilar-Gaxiola, María Elena Medina-Mora, and Gustavo Loera

CHAPTER 11. Urbanization and Theoretical Perspectives on Migration and Mental Health

Yang Xiao

CHAPTER 12. Nutrition and Migrant Health

Erin Hoare, Adrienne O’Neil, and Felice Jacka

CHAPTER 13. Sexual, Reproductive, and Maternal Health in the Context of Migration

Sónia Dias, Ana Gama, and Patrícia Marques

CHAPTER 14. Unique Health Considerations during Forced Displacement

Sabrina Hermosilla and Janna Metzler

CHAPTER 15. Older People, Health, and Migration

Tony Warnes

CHAPTER 16. The Health of Migrant Children

Ayesha Kadir and Anders Hjern

CHAPTER 17. Violence, Migration, and Mental Health

Jutta Lindert

CHAPTER 18. Remittances, Health Access, and Outcomes

Melissa Siegel

CHAPTER 19. Technology and Migrants’ Health: Access, Opportunity, and Ethical Challenges

Ebiowei Samuel F. Orubu, Carly Ching, Ahsan M. Fuzail, and Muhammad H. Zaman

CHAPTER 20. Intersectionality: From Migrant Health Care to Migrant Health Equity

Denise L. Spitzer

CHAPTER 21. The Ethics and Justice of Recognizing Migrants’ Right to Health

Wendy E. Parmet

PART IV. Approaches to Understanding the Relationship between Migration and Health

CHAPTER 22. The Relevance of Culture for Migrant Health

Tilman Lanz

CHAPTER 23. The Sociology of Migration and Health: The Decline in Migrants’ Health Due to Adverse Environments and Limited Options for Care

Steven J. Gold

CHAPTER 24. Economics in Migrant Health: Migrant-Sensitive Service Improvement as a Driver for Cost Savings in Health Care?

Ursula Trummer, Lika Nusbaum, and Sonja Novak-Zezula

CHAPTER 25. Multilevel and Mixed-Methods Studies of Migration and Health

Joshua Breslau and Lilian G. Perez

CHAPTER 26. Epidemiology and the Study of Migrant Health

Nadia N. Abuelezam

CHAPTER 27. The Humanities of Migration and Health

Carrie J. Preston

CHAPTER 28. Law, Migration, and Health in the US Context

Sondra S. Crosby, Michael R. Ulrich, and George J. Annas

CHAPTER 29. Migration: A Health-Equity Lens

Felicity Thomas

PART V. Case Studies in Migration and Health

CHAPTER 30. The United States as a Case Study: Policy, Access, and Outcomes

Sana Loue

CHAPTER 31. Eastern Mediterranean and Balkan Migration Route

Karl Philipp Puchner

CHAPTER 32. Migration and Health in Nepal

Sabrina Hermosilla, Emily Treleaven, and Dirgha Ghimire

CHAPTER 33. Persian Gulf Migrants

Maria Kristiansen

CHAPTER 34. South Africa

Jo Vearey

CHAPTER 35. Migration and Health in China

Bingqin Li

CHAPTER 36. Asian Immigrants in New Zealand

Eleanor Holroyd and Jed Montayre

CHAPTER 37. Mobility and Health in the Pacific Islands

Celia McMichael

CHAPTER 38. Venezuela and Latin America

Oscar A. Bernal Acevedo, Jovana A. Ocampo Cañas, Jhon Sebastian Patiño Rueda, Laura Baldovino-Chiquillo, and Salma S. Baizer Cassab

CHAPTER 39. The South Asian Context

Muhammad H. Zaman, Reshmaan Hussam, and Hulya Kosematoglu

PART VI. The Future of Migration and Health

CHAPTER 40. Preparing the Next Generation of Scholars in Migrant Health

Zelde Espinel and James M. Shultz

CHAPTER 41. Migration and Health: Taking Stock and Looking to the Future

Muhammad H. Zaman, Catherine K. Ettman, and Sandro Galea

Acknowledgments

List of Contributors

Notes

Index

PART I

Why Migration and Health?

CHAPTER ONE

An Introduction to Migration and Health

Sandro Galea, Catherine K. Ettman, and Muhammad H. Zaman

1.0 Introduction

Population migration—the movement of people across and within borders—has long been, remains today, and will likely continue to be one of the central demographic shifts shaping the world around us. It is therefore unsurprising that population migration is also associated with the health of populations. The world’s history—and its health—is shaped and colored by stories of migration patterns, the policies and political events that drive these movements, and narratives of individual migrants. Petroglyphs in Azerbaijan, more than ten thousand years old, depict humans migrating.¹ Europeans’ migration to the Americas resulted in widespread infectious disease outbreaks, affecting the health of millions of native Americans and also changing the history of the world as the Americas emerged as an important center of geopolitical power. Marie Curie migrated from her native Poland to Paris, where she carried out groundbreaking science, doing work that was instrumental to establishing radiology and becoming the first person in history to receive two Nobel Prizes. These are just some examples of the formidable influence of migration on human advancement.

2.0 The Global Demographics of Migration

Migration, therefore, is an indelible part of human history. It is increasingly so today. Together with population aging and urbanization, the movement of people within countries and across international borders is rapidly coming to define the mid-twenty-first century. A brief summary of the current demographics of migration illustrates the scope of the impact migration has on the world.² It is estimated that there are 272 million international migrants today, about 3.5 percent of the world’s population. This is an increase from the 258 million international migrants in 2017, which itself was a 50 percent increase since 2000. If international migrants made up one country today, they would be the fifth largest country in the world after China, India, the United States, and Indonesia.

The countries that are the largest recipients of migrants overall are the United States, followed by Saudi Arabia, Germany, and the Russian Federation. One hundred forty-one million—more than half—of all international migrants live in Europe or North America. In North America, more than 40 percent of population growth is accounted for by positive net migration. India, Mexico, and China are the countries with the largest number of migrants living abroad. Internal migration represents an even larger flow of populations globally, with about 750 million persons being internal migrants. Taking internal and external migration together, about one in seven people globally are migrants. A number of cities now house more people from other countries than those who are native to the country itself, and it has become unsurprising to find foods from all corners of the world readily available in global cities.

Out of the 272 million international migrants globally in 2019, 74 percent were between the ages of twenty and sixty-four (i.e., working age adults who contribute substantially to the economies of their country of origin and their host country). Global remittances sent by migrants back to their country of origin topped 689 billion US dollars in 2018, with the top three remittance recipients being India, China, and Mexico. The United States is the leading remittance-sending country, consistent with its status as the country receiving the most migrants, followed by the United Arab Emirates and Saudi Arabia. There is substantial variability in migration patterns from region to region. Most international migrants born in Asia, Africa, and Europe stay within their regions of birth, while the majority of migrants from Latin America, the Caribbean, and North America live outside their regions of birth. The number of refugee and asylum seekers is estimated at around 14 percent of the total number of migrants. The Syrian Arab Republic was the origin—and Turkey the recipient—of most refugees globally. Canada is the country that hosts the most permanently resettled refugees.

Such large population demographic shifts might be reasonably expected to affect many aspects of populations, including how cities are organized and evolve, who lives in rural areas, the foods we eat, the people in our neighborhood, and our social networks. These shifts also have been responsible for some of the most heated political rhetoric of the past decade, as nativist political leaders all over the world have used an othering of migrants to drive narrow political agendas, resulting in seismic political shifts ranging from the United Kingdom to China. Several chapters in this book present data about the impact of migration on demographic shifts and how those demographic shifts are shaping the world around us.

3.0 Key Definitions in Migration

Chapters of this book make use of definitions relevant to migration that are particular to their area of inquiry and reflect the substantial variability in the realities of migration within and across regions. However, we recognize, as have others, that some of these definitions may present challenges in measurement and comparability across contexts.³ Therefore, we offer a brief synthesis of the most relevant definitions around migration. At the most fundamental level, migration refers to the movement of people, individually or in groups, as well as persons moving within or between countries. The International Organization for Migration defines a migrant as anyone who has moved either across borders or to a state outside the person’s habitual residence.⁴ Migration can be voluntary or involuntary, transient or permanent. Short-term migration is generally considered to be three to twelve months, while more than twelve months is considered to be long-term. People may pass through several countries and stay for varying periods of time in several states before eventually reaching a place where they live for an extended period. In the past two decades, circular migration has also become more common, with migrants moving temporarily for economic opportunities and returning to their home countries.

Migration can happen for any range of reasons, such as economic or environmental, and can be initiated by the migrants themselves or by official efforts to expel them from their home country. Forced migration is generally considered to be migration that is propelled by an external compelling reason, such as violence or disasters. Voluntary migration is, in contrast, considered to be migration initiated at the person’s choice. The boundaries demarcating these definitions are clearly not rigid and have evolved over the years. While a person who is migrating to improve economic context may not be forced to migrate, it is entirely plausible that that person felt little choice but to migrate to improve their or their children’s opportunity set. A forced migrant may also become an economic migrant during the course of his or her lifetime or even in the course of the journey. In addition, formal definitions distinguish between internal migration (movement within a country) and external migration (movement across countries). Persons who are migrating across nation states owing to fear of persecution for reasons of race, religion, nationality, or membership in a particular group are called refugees. Persons who are awaiting decisions on their refugee status are called asylum seekers. We refer the reader who is interested to some very good work that includes more comprehensive definitions of different types of migrants,⁵ as well as official United Nations reports on the topic.⁶

4.0 This Book’s Approach

There is a growing body of scholarship in the field of migration and health, and more scholars are dedicating themselves to the field. This is all heartening and, to our minds, commensurate with the importance of this area of inquiry. Therefore, this book, grounded in the scholarship that has come before us, aims to be a comprehensive text that interrogates the complex relationship between migration and health, bringing to bear insights from across disciplines to do so. This book is predicated on the idea that understanding how migration affects health requires a comprehensive grappling with the processes that explain migration and a rigorous analysis of the consequences of migration for the health of populations.

Three observations may be helpfully grounding to readers of this book.

First, migration matters, and it matters to the health of populations. How migration intersects with and affects the health of populations is complex and is not readily reduced to simple summaries. This book is premised on the importance of the role migration plays in shaping health and also of the complexity of the relationship between migration and health. It is important to note that the relation between migration and health cannot readily be reduced to simple risk factor and health outcome dichotomies. Migration is, in and of itself, not harmful to health, in much the same way that, for example, urbanization is not as a single entity harmful to health. Rather, there are features of migration that influence health—some positively, some negatively. What is of interest is not the reductive simplification of a linear, predictable relationship between migration and health, but rather a full understanding of the features and processes of migration that matter for the health of populations. One of the challenges with these ideas in a book such as this one is that the chapters are written by experts in one aspect of migration and health and the focus is often on why that aspect challenges the health of migrant populations. This may leave the reader with the impression that migration is a net negative, which is not the case. If it were, it is unlikely that migration would have long been such an important—and growing—force in the world. Migration in the net exists because migrants move to better and healthier lives. However, an exploration of migration and health casts a spotlight on the aspects of migration that negatively affect health with the goal of identifying those elements so that we can intervene and do better. Insofar as this book helps hold a magnifying glass to those processes, it is doing its job to help motivate action on improving the health of migrants.

Second, those affected by migration include both the receiving (host) populations and migrants themselves. That association, however, is not straightforward. There is the health of the migrants themselves. The health of migrants is a product of the migrants’ baseline health—generally better than that of the population where the migrants came from—of the migration experience, and of the social, economic, mental, and physical conditions that the migrants encounter in their destination. There is also the health of the migrants’ descendent groups. As populations assimilate in new environments, health behaviors and exposures change, often resulting in subsequent generations being less healthy than the migrants themselves. There are important issues in health access, nutrition, disease exposure, and health policies at the intersection of migrant and host populations that have short- and long-term impacts on the community as a whole. Communities are shaped and reshaped by waves of migration, changing local social and economic environments in a way that influences the health of all within these populations.

Third, this book builds on existing scholarship and expertise, aiming to be a synthesis of what we know and how we think and to push the field forward. Although we tried to address the dominant challenges in the field, the book is limited in areas where the field is limited. For one, the book, by design and intention, does not focus on either internal or global migration, as it considers the migratory journey—be it domestic or international—to be just one part of the set of forces shaping how migration affects health. That design tilts the chapters of the book to focus more on international migration than on intranational. This reflects the preponderance of academic work, and that is in turn driven by the much more readily apparent international migrant populations, rather than internal migrant populations. In a similar vein, the scholarship documented here represents more perspectives of migration from low- and middle-income countries to high- or higher-income countries than of migration among low- and middle-income countries. This reflects the state of the scholarship, but we note it here as a call for future action and as a marker for readers who are using this work to ground their learning in the field. And, finally, reflecting the state of the field, different chapters in the book sometimes bring different conceptual lenses and approaches to their subject matter. While this is a common challenge with edited volumes like this one, it is particularly true for a field that is as much in its infancy as is migration and health. This book aims to weave together data from different disciplines to create a framework for understanding the relationship between migration and health that can serve us well as we move to the middle of the twenty-first century, where migration is increasingly shaping where and how we live. Although we have worked with the chapter authors on harmonizing key aspects of each contribution to the broader agenda of this volume, we opted to allow for heterogeneity of perspective where there was such, leaving that to reflect genuine differences between authors, and respecting readers’ discernment to develop their own narrative, informed by the state of the field.

This book is divided into six parts. First, we present a comprehensive framework from which the reader can understand the issue of migration and population health. Second, we discuss the mechanisms that intersect with migration to shape population health. Third, we discuss particular topics that intersect with migration and health—the domains in which migration’s health impacts manifest. This part will discuss, for example, nutrition, aging, maternal and reproductive health, mental health, access to health care, and the health of children. The fourth part brings a methodologic lens to the topic, bringing together authors who approach the issue from different disciplinary perspectives, including, for example, anthropology, sociology, economics, engineering, and epidemiology. The fifth part includes case studies, focusing on countries and regions like Nepal, the United States, China, and the Persian Gulf, where migration has been increasingly shaping the political, social, and economic milieu over the past decade. We end with a part about the future of migration and health, focusing on how we can best educate the next generation of scholars in the area, articulating areas where the field can productively grow, and answering questions that need to be answered to the end of improving the health of populations.

It is our hope that this book represents a comprehensive text that synthesizes the state of the science surrounding human migration and health. To us, the study of migration and population health represents an exciting evolution in an interdisciplinary field. As more scholarship emerges in the area, the opportunity for transdisciplinary synthesis increases, paving the way for a whole new scholarship that helps us better understand the particular challenges and opportunities presented by migration and health as it adopts methods and approaches from long-established disciplines. The synthesis, therefore, aims to do more than summarize; it aims to clarify what we know and what we do not know to the end of informing what we do today and what we shall do in the coming decade. We are publishing this book at a time when we think we are at an inflection point in the field of migration and health. This book aims to be part of the movement toward making that inflection steeper and to help point it in the right direction and will hopefully aid the teachers, scientists, and programs in the field that will emerge. We look forward to reading and learning from the scholarship that shall emerge as other authors and thinkers build on this work to advance our understanding of migration and the health of populations.

CHAPTER TWO

Understanding Migration and Health

Social-Ecological and Lifecourse Perspectives

Catherine K. Ettman, Muhammad H. Zaman, and Sandro Galea

1.0 Introduction

The first chapter of this book framed how migration has been a major driver in population movement and that trends past, present, and future indicate that migration is, and will remain, an important driver of the health of populations in coming decades. Migration, whether forced due to conflict or climate change or driven by economic incentives, shapes health in a number of ways. This chapter aims to provide three frameworks that can be useful in organizing our thinking about migration and health in particular: the social-ecological model, the lifecourse perspective, and the migration process itself. The chapter will discuss how these three frameworks may be used to understand the relation between migration and health, anchored in mental health as one example of a health indicator influenced by migration. We first introduce the three frameworks, and then we expand with specific examples using each framework. We conclude by summarizing the goals of the book and how these concepts will be addressed throughout the volume.

2.0 Three Frameworks

2.1 The Social-ecological Model

Health is the product of a set of influences, at multiple levels, ranging from the personal to the societal, that intersect, modify each other in a mutually codependent manner, and produce health.¹ The social-ecological model summarizes how multiple levels of context produce health in persons. Personal—and population—health is a product of social relationships, living conditions, neighborhood conditions, institutions, and social and economic policies that govern the places where populations live.² This is true of all people and particularly of people who migrate. Figure 2.1 shows how the health of people who migrate is a function of multiple levels of context across multiple levels. The health of persons who migrate is in part a product of the social, environmental, and political institutions and public resources available in their country of birth, current country of residence, and any countries where they may have lived over the lifecourse. In this way, personal relationships, physical living conditions, neighborhoods, institutions, and national policies influence the health of migrants.

FIGURE 2.1. Social-ecological framework for understanding health, in the context of migration

Source: Modified from Kaplan, George A., What’s Wrong with Social Epidemiology, and How Can We Make It Better? Epidemiologic Reviews 26, no. 1 (2004): 124–35, https://doi.org/10.1093/epirev/mxh010.

2.2 The Lifecourse Perspective

Exposure to contexts—and their influence on health—varies throughout the lifecourse. Birth and death bookend health throughout the lifecourse. Exposures in utero and during critical development periods in childhood and adolescence influence later health outcomes. The experience of migration can expose persons to contexts that improve or harm health, and when that exposure happens also influences the importance of each factor. The lifecourse approach allows us to visualize how experiences mount over time to accumulate in health.³ Figure 2.2 describes health as a function of life stage across five periods: prenatal, infancy and childhood, adolescence, adult life, and older age. Although the demarcation between each stage is ultimately arbitrary, conceptually each stage presents unique opportunities and challenges for health for all people. A lifecourse framework can help situate how experiences that are unique to persons who migrate can affect their health in different ways at different periods in their lives. Figure 2.2 highlights health risks at every developmental stage and how exposure to them can cause good or poor health. It also shows that health is cumulative over the course of a person’s life. The migration process can influence health in different ways, depending on when in life and how a person migrates.

FIGURE 2.2. Health across the lifecourse, in the context of migration

Source: Adapted from Uauy, Ricardo, and Noel Solomons, Diet, Nutrition, and the Life-Course Approach to Cancer Prevention, Journal of Nutrition 135, no. 12 (2005): 2934S–45S, https://doi.org/10.1093/jn/135.12.2934S.

2.3 The Migration Process

Migration itself is a complex and multipart process. The migration process framework shows simplified stages, within which exposures can influence health. Figure 2.3 shows one possible three-step process of migration with a potential fourth step: premigration, movement, arrival and integration, and return. Health may intersect with each phase, and understanding what exposures occur and when they happen in the course of the migration process can help to organize our understanding of how these factors shape health.⁴ This framework is a generalized one, and variations exist based on context. There are many other context-specific scenarios, but this framework aims to present a more generalized approach to considering the various stages of migration and health.

FIGURE 2.3. The determinants of health through the migration process

Sources: Modified from Vearey, Hui, Wickramage, Migration and Health: Current Issues, Governance, and Knowledge Gaps, World Migration Report (2020): 209–28. Figure 1. The Determinants of Migrant Health throughout the Migration Cycle, adapted from Gushulak, Weekers, and MacPherson, 2009; IOM, 2008, https://publications.iom.int/books/world-migration-report-2020.

3.0 Applications of the Frameworks

Here we use the example of mental health to show how these three frameworks can be applied in organizing how migration affects health. Mental health is sensitive to physical, economic, and social contexts, and may present sooner than physical health disparities;⁵ additionally, mental health is inseparable from physical health, with mental illness associated with additional comorbidities.⁶ Thus, the mental health effects of migration may serve as an effective illustrative example of the application of these frameworks on understanding migration and health. The examples cited below are used for illustrative purposes; chapter 10 will delve into greater depth on the topic of mental illness, substance use, and migration. The processes in the three frameworks featured—the social-ecological model, the lifecourse perspective, and the migration process—serve as organizing metaphors, helping us better understand what are ultimately complex and dynamic relations that produce health.⁷

3.1 Social-ecological Model

The social-ecological model can help organize our thinking around the relation between migration, context, and health. The social-ecological model reflects the multiple contexts within which people live and within which health is ultimately realized. Experiences in social relationships, living conditions, neighborhoods, institutions, and social and economic policies shape personal and population health,⁸ and in particular the health of migrant populations.⁹

Starting at the personal level, personal characteristics, including genetic traits and dispositions, influence health. It is not at all clear if migrants overall have better or worse mental health than nonmigrants. A healthy migrant effect has been noted, where persons who are able to migrate have better health than their native-born counterparts, potentially representing a health selection bias in those who are able to migrate.¹⁰ Although some studies show a physical health¹¹,¹²,¹³ and a mental health advantage,¹⁴ there is substantial heterogeneity of findings across subpopulations.¹⁵ For example, immigrant mothers in Canada exhibit worse mental health than their native-born counterparts.¹⁶ Fundamentally, it is competing forces over the social-ecological model that influence the production of mental health in migrant populations.¹⁷,¹⁸,¹⁹ Chapter 4 will expand on the health of persons before migration and the healthy migrant effect, adding to our understanding of personal constitutional factors and individual risk factors before, during, and after migration.

At the social relationship level, family and interpersonal relationships can serve to protect against or exacerbate poor mental health of persons who migrate. For married female immigrants, spousal alcohol consumption, intimate partner violence, marital distress, and family-related stressors such as intergenerational cultural conflict are associated with poor mental health.²⁰,²¹,²² Numerous studies document the effect of parental mental health on children²³ and of the separation of families, such as the ill effects of parental migration on children left behind.²⁴ The experience of parenthood and family dynamic is shaped by the heterogeneous experiences of migration, leading to improved or deteriorated health outcomes.²⁵ Positive factors such as family efficacy,²⁶ ethno-cultural identity, and broader social support can serve as a protective factor against ill health.²⁷,²⁸,²⁹

Living conditions shape many measures of health.³⁰ For migrant populations in particular, their living conditions may be a function of their resources and the terms of their migration. Housing instability and substandard living conditions have been well documented among migrant farm workers,³¹,³²,³³ temporary foreign workers,³⁴ and general migrant populations.³⁵ Substandard housing may include crowding, mold, mildew, structural deficiencies, and pesticides, which in turn can cause poor mental and physical health.³⁶,³⁷,³⁸ Access to living conditions is in no small part a function of economic status, with low economic resources leading to poor or unsafe housing conditions among migrant populations.³⁹,⁴⁰

At the neighborhood level, environmental factors shape the context in which migrant populations live. Neighborhood characteristics such as violence, walkability, access to healthy foods, and green space have been associated with health outcomes among refugee and migrant populations.⁴¹,⁴² Living in disadvantaged neighborhoods has been shown to be associated with withdrawal, somatic complaints, and depressive/anxious behaviors in first- and second-generation immigrant adolescent Latinx populations in the United States.⁴³ Similar associations have been observed for other health conditions. For example, refugees assigned to live in more disadvantaged neighborhoods in Denmark were found to have increased risk for hypertension, diabetes, and myocardial infarction several decades later than their counterparts placed in wealthier neighborhoods.⁴⁴ In this way, exploring characteristics of neighborhoods that migrants have lived in, both before and after migration, can help in our understanding of mental and physical health among populations who migrate. Chapter 12 will assess nutrition, exploring in part how access to healthy foods, as a function of neighborhood resources, leads to improved health. Chapter 17 will expand on violence and health, touching on exposures to violence at different stages of migration.

Interactions with public, private, and civic institutions can harm or promote migrant health. Interactions that shape health may occur in workplace, medical, and religious and cultural institutions, as examples. Migrant employees may face greater discrimination or risk of injury at the workplace than nonmigrant employees, as has been documented in nurses,⁴⁵ farm workers,⁴⁶ and other workers.⁴⁷ Interactions with medical institutions have been well established as unequal between immigrant and nonimmigrant populations for a number of reasons.⁴⁸,⁴⁹ International migrant children use health-care services such as general, primary, and dental care less than native-born children, with the exception of hospital and emergency services.⁵⁰ For mental health care use in particular, lack of insurance, high costs, and language barriers have been reported as key obstacles to access among immigrant populations.⁵¹ Interactions with other organizations, such as religious and cultural institutions, can facilitate social support, which in turn protects against poor mental health. For example, older Latinx women in the United States who attended regular church services reported lower levels of depression before and after a spouse’s death than their counterparts who did not regularly attend.⁵² Chapter 3 discusses global drivers that shape health, which often overlap with institutional engagement. Chapter 6 explores migration and access to health care in particular. Chapter 20 expands on interactions between migrants and systems more broadly. Engaging institutions may be influenced by the macro level of the social-ecological model, in which national policies shape contexts in which migrants live.

The macro-determinants of health include the social and economic policies that shape migrant experiences at all other levels. Examples of policies that may particularly affect migrant populations are those around immigration, health-care coverage, access to a social safety net, and discrimination. Broadly, recognition of legal status of migrant populations allows for access to a whole suite of public resources that improve mental and physical health. Restrictive policies for migrant entry and legalization are associated with poor health in migrant populations in high-income countries.⁵³ Countries with robust social safety-net programs may more readily provide access to health care, housing, and food, translating to better health for all residents and particularly for the health of its migrant populations.⁵⁴,⁵⁵ Access to health care in particular also varies by country. The United States does not provide health care as a human right, and policies such as expansion of the definition of public charge to include Medicaid use may also stifle the use of health care for persons who migrate. Immigrants in the United States who use social services for twelve months within a thirty-six-month period including food assistance, housing assistance, or Medicaid can be denied visa extension or entry to the United States due to their potential charge to the public.⁵⁶ Fear of using public assistance for determinants of health such as housing or nutritional services may lead to widened health gaps between migrant populations and nonmigrant populations. However, even in countries that provide universal health-care coverage, such as Canada, barriers to care still exist for immigrant populations. Barriers to accessing care include language barriers, cultural barriers, and barriers in navigating services.⁵⁷ Finally, policies that discriminate against ethnic minorities or that remove protections from discrimination are associated with worse mental health outcomes. In 2017, the United States limited immigration for persons from a set of countries that have majority Muslim populations. Those policies, coupled with an increase in Islamophobia and discriminatory acts, were associated with an increase in poor mental health.⁵⁸ Discrimination has been well documented to lead to poor mental health in migrant and non-majority populations in general⁵⁹ and Latinx,⁶⁰ Arab American,⁶¹ Asian,⁶² and refugee populations in particular.⁶³ Laws, policies, and practices at the broader national and societal level can promote health or worsen health. Chapter 8 will explore global governance and the health of migrants. Chapter 28 will explore the relation between law, migration, and health in the US context. Chapter 21 will discuss the concepts of ethics and justice surrounding migrant health and will touch on the macro-social and economic policies shaping the health of populations who migrate.

The social-ecological model serves as one framework to organize the connection between the multiple, complex causes of health and the migrant experience. It should be noted that persons who migrate live under multiple contexts; many of the studies mentioned in this chapter refer to immigrant populations, citing the associations between context and health after persons have migrated. Additionally, migration can also be seen as a continuous process or one that does not end. A person’s health will be the function of his or her cumulative life experiences; thus, their contexts before, during, and after migration matter, as well as their age and life phase when the exposures occur.

3.2 Lifecourse Framework

A second framework that may be useful for considering the health of persons who migrate is the lifecourse framework. Figure 2.2 shows health across the lifecourse, in the context of migration. Health happens over the lifecourse, with exposures before birth influencing outcomes and with health slowly deteriorating over a life until eventual death. As such, experiences at different developmental moments affect health differently. For example, maternal violence or exposure to violence in the surrounding environment during pregnancy is linked to developmental difficulties in children.⁶⁴ Adversity in childhood⁶⁵ and adolescence⁶⁶ has been linked to negative health outcomes including obesity, asthma, and recurrent infections requiring hospitalization.⁶⁷ A robust literature exists on the health and behavior of children who migrate in particular, although this work is limited by a reliance on parental or adult accounts of children’s experiences.⁶⁸ Risky behavior during adulthood, such as consumption of alcohol and tobacco and physical inactivity, leads to ill health. Finally, in older age, factors such as social isolation can lead to poor mental health outcomes.⁶⁹

Health benefits and risk accumulate over time and are a function of when in his or her lifetime a person migrates. Differences in psychological distress may be explained by exposures over the lifecourse.⁷⁰ For example, exposure to reduced social cohesion, lower socioeconomic status, and discrimination account for a large portion of differences in health between native-born and non-native-born persons. In Sweden, poorer self-rated health was associated with later age of migration and fewer than fifteen years of residence in the country.⁷¹ In the United States, Australia, and Canada, the health outcomes of immigrants converge with those of native-born residents after residency in the host population for ten to twenty years.⁷² While people who migrate to these countries may be healthier to begin with, those benefits appear to fade through aging and assimilation.⁷³ Exposure to different experiences and environments at different points in time will translate to different health outcomes. In this way, persons who migrate will have unique health outcomes depending on the intersection of their experiences in place and time over the course of their lives. Thus, age and experiences through the lifecourse matter for all persons and particularly for persons who migrate, and the lifecourse approach offers another tool to organize our understanding of migration and health. Chapter 16 explores the health of children in particular, and chapter 15 explores the health of older people. Health risks vary depending on life stage during migration,⁷⁴ leading to the third framework to consider.

3.3. Migration Process

A third framework that may be helpful for considering migration and health is the migration process framework. Figure 2.3 shows the distinctive stages of migration: premigration, movement, arrival and integration, and potential return. The experience of migration at any of these phases may shape health. Premigration experiences have been found to shape mental health in youth.⁷⁵ Having a high socioeconomic status premigration may not necessarily protect refugees from the ill effects of migration during or after the first few years of integration.⁷⁶ The movement phase can expose people to stressors that in turn affect mental health.⁷⁷ For example, exposure to violence during migration leads to poor mental health.⁷⁸,⁷⁹ Similarly, experiences during arrival and integration can affect both physical and mental health outcomes.⁸⁰ Exposures during the first year of arrival also contribute to youth mental health⁸¹ and adult health. Persons who experience downward social mobility upon migration are more likely to report poor mental health than persons who experience upward or unchanged mobility.⁸² Persons who migrate may face different risks of infectious disease across each stage of migration.⁸³ Additionally, for some communities, the process of migration may not end, and these populations may continue to move and may remain displaced for long periods. It is important to note that while migration can be a stressful exposure, not all persons who migrate go through the same process and, therefore, their health outcomes may vary as a result.⁸⁴ The migration process framework, however, may serve as an additional mechanism for organizing and understanding the connection between migration and health. Chapter 5 explores more fully health and the process of migration. Chapter 14 expands on forced migration, and Chapter 17 discusses the impact of violence through all migration phases on health.

4.0 Conclusion

Ample evidence shows that migration is a factor in population health. Additionally, health is a function of context, and context matters across the lifecourse. Differential experiences across contexts have led researchers to identify immigration itself as a social determinant of health.⁸⁵,⁸⁶

This chapter presented three frameworks to guide our thinking on migration and being a migrant: the social-ecological model, health across the lifecourse, and the migration process. In sum, these three frameworks can help focus research and action that address how health is influenced by context, which affects health throughout the lifecourse and through stages of migration. These are but three frameworks to use; there are countless others, many of which will be discussed throughout this volume. We offer these three at the outset, presenting them as overall frames within which subsequent chapter-specific discussions can be situated.

CHAPTER THREE

The Global Drivers of Migration

Francesco Castelli

1.0 Introduction

Migration is an extremely complex phenomenon that leads individuals, families, entire communities, or even mass populations to move definitively from their usual place of residency.

During the last fifty years, the absolute number of international migrants has more than tripled, from 84 million in 1970 to nearly 272 million in 2019.¹ However, the proportion of international migrants over the total world’s population has only risen from 2.3 percent to 3.5 percent over the period, and especially so during the last thirty years, when the proportion rose from 2.9 percent in 1990 to 3.5 percent in 2019 (table 3.1). Of note, contrary to public perception, international migrants from the South are equally relocated in both Southern and Northern countries. In 2018, the number of asylum seekers and refugees was estimated to be twenty-six million globally.²Apart from international migrants, as many as 740 million individuals are estimated to have moved internally away from their usual place of residency to other areas in the same country.

TABLE 3.1 International migrants by calendar year, 1970–2019

Note: International Organization for Migration (IOM), World Migration Report 2020, accessed October 10, 2020, https://publications.iom.int/system/files/pdf/wmr_2020.pdf.

The rising absolute flow of migrants in the last two decades has sometimes prompted a negative reaction from the host communities in the Western industrialized world, fueled by prejudices regarding safety and health issues.³ Although the health profile of migrants may vary according to their geographical provenance, the infectious risk to the host communities has been proven negligible from a public health perspective.⁴

According to the various factors that drive migrations and that often act in combination, attempts have been made to classify the heterogeneous population of migrants, summarized in chapter 1.⁵ However, it should be noted that the motivations forcing people to permanently leave their country of origin may even change during the migration process as the situation changes and evolves, as was the case for Afghan children arriving in Belgium.⁶ Further, most economic and sociopolitical drivers are strictly interconnected, as sometimes even push and pull factors are and often hardly separable from one another, making mutually exclusive classifications most probably overly simplistic.

The literature exploring the causes of migration flows is often divergent and contradictory, largely because the perspective of the authors differs from methodological (quantitative versus qualitative studies) and geopolitical or socioeconomic standpoints.⁷ Given the complexity of the matter, a multidisciplinary effort is needed to appreciate the evolving nature of the causes of such a relevant phenomenon that has a profound social and economic impact on both origin and hosting societies.

The classic push and pull framework trying to describe and classify the global drivers of migration was initially proposed by Everett S. Lee in 1966.⁸ Briefly, the push and pull theory tried to identify those negative elements that may affect satisfactory life in the country of origin (e.g., conflicts, dictatorships, discrimination, unemployment, low wages, etc.) leading to the migratory project (push factors), and those attracting factors (pull factors) that conversely are regarded as positive elements to ameliorate the life of the individual and of their family (e.g., welfare, job opportunities, peace, presence of co-ethnic communities, etc.). Lee also addressed the issue of intervening obstacles that may prevent migration despite the presence of effective push and pull factors. The push and pull conceptual frame has the advantage of linearity and simplicity. However, it fails to explain why, for example, people living in the same area and suffering from the same negative conditions may make different choices with regards to migration or why the same area may be at the same time a place of emigration and immigration.⁹ Other elements to be taken into consideration include individual characteristics and aspirations within a broader evolving socioeconomic perspective. To overcome the limit of the somehow static push and pull theory while maintaining its linearity and clarity, some authors have proposed a revised version called push and pull plus.¹⁰ The push and pull plus framework tries to assess the impact of structural (pushing and pulling) macro-factors on the individual characteristics of the subject (micro-level) or their social network (meso-level), leading to the final decision to migrate or not to migrate.¹¹

2.0 Drivers of Migration

The following is a brief description of the evidence supporting the roles of the main structural macro (pushing and pulling) and the meso and micro factors—most often acting in combination—in determining the final individual decision to move.

2.1 Pushing Macro-factors

Pushing macro-factors are those factors producing dangerous or unpleasant living conditions in one specific area that act as expelling forces and are not under the control of the individual or the community.

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2.1.1 DEMOGRAPHIC INCREASE, URBANIZATION, AND POPULATION DENSITY. The world population has sharply increased in the last two centuries, from the estimated 1 billion individuals living in the year 1800 to the nearly 7.8 billion reported by the United Nations Department of Economic and Social Affairs (UNDESA) in the year 2020. However, the increase in population has not been even in the different parts of the world. Between 1950 and 2020, the African population increased from 227 million to 1.340 billion (+490%) and the Asian population from 1.404 billion to 4.641 billion (+230%). In the same period, Europe has grown from 549 million to 747 million (+36%) and North America from 172 million to 368 million (+113%), a much lower increase as a result of different fertility rates in Africa (4.4 live births/woman in the period 2015–2020), Asia (2.15), Europe (1.61), and North America (1.75).¹² According to UNDESA forecasts, given the existing conditions, the world total population will approach eleven billion in the year 2100, with Africa and Asia totaling nine billion individuals and Europe experiencing a shrinking of its population to 629 million. The net result will be a progressive demographic decline characterized by an aging population in today’s Western industrialized countries, compared to a much younger working-age population living in resource-limited countries in the Global South. This demographic unbalance is coupled with the progressive urbanization rate taking place in Africa (from 14.3% in 1950 to 43.5% in 2020) and Asia (from 17.5% to 51.1%), exposing younger generations to an increasingly densely populated urban environment with a strikingly uneven wealth distribution.

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2.1.2 INADEQUATE HUMAN AND ECONOMIC DEVELOPMENT, THE INVERSE U CURVE. The United Nations Development Programme (UNDP) created the Human Development Index (HDI) in 1990 to rank the state of development of any individual country. The HDI is a complex indicator assessing the three key dimensions of development: healthy life, knowledge, and standard of living, respectively measured by life expectancy at birth, years of schooling for adults aged twenty-five or more, and gross national income per capita. The top twenty HDI ranked countries in 2019 are European (13), North American (2), and Australasian (3), while as many as eighteen out of the bottom ranked twenty countries belong to the African continent, with gross national income per capita ranging from US$68,059 to US$912.¹³ Although the African continent has witnessed remarkable economic growth in the last decades, the distribution of wealth in African resource-poor countries has not been even, leaving a large majority of the workforce in the poorly profitable informal sector without social security coverage. Interestingly enough, the educational gap between the countries with a very high human development index (12 years of schooling, on average) and developing countries (7.4 years of schooling) is not as dramatic as the economic gap, as a probable result of the ongoing efforts put in place to reach the Millennium Development Goals and the Sustainable Development Goals.¹⁴ Evidence points to the fact that initial economic development in a given low-income country is not immediately followed by a fall in the emigration rates, but rather by an increase. Only when development has reached a certain level does emigration tend to lower, a pattern referred to as the inverse U curve theory.¹⁵

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2.1.3 DISEASE PREVALENCE AND HEALTH SYSTEMS. In 1978, the World Health Organization launched the Health for All goal, based on the implementation of the Primary Health Care (PHC) strategy and on the strengthening of the health systems in resource-poor countries, to be reached by the year 2000.¹⁶ Many economic and political factors have prevented the full implementation of the PHC, leading to large health sector privatization and out-of-pocket expenses and leaving many poor people entrapped in poverty with little access to health-care services.¹⁷ The Millennium Development Goals, launched in the year 2000 and targeted to 2015, have contributed significantly to ameliorating the living conditions of resource-poor settings, but the infant mortality rate in low-income regions in 2015 was still 47 per 1,000 live births (compared to 6/1,000 in developed regions) and the maternal mortality rate was 230/100,000 live births (compared to 16/100,000).¹⁸ The Covid-19 pandemic is expected to set back all the Sustainable Development Goals indicators to a large extent, making living conditions in resource-poor settings worse.¹⁹ However, little is known about the role of disease prevalence and access to care on migration flows.

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2.1.4 CLIMATE CHANGES, FOOD, AND WATER SECURITY. Little doubt exists that the planet has undergone a warming process largely due to the emission in the atmosphere of greenhouse gases (in particular carbon dioxide, methane, and nitrous oxide) of an anthropogenic nature.²⁰ Most greenhouse gases enter into the atmosphere by affluent countries (estimated 97%),²¹ but the most negative consequences even in terms of mortality are suffered by resource-poor countries.²² The warming of the planet has many negative environmental consequences possibly influencing the final decision to migrate. First, it may cause dryness and drought in large areas, making the soil unsuitable for cultivation and breeding and eventually leading to severe food insecurity. Such conditions may affect vast areas in sub-Saharan Africa (for example, those surrounding Lake Chad) and other arid zones in Asia and Latin America. Further, extreme weather events may have a direct impact on health conditions of the populations. Second, it may facilitate the incidence and prevalence of communicable (vector borne and waterborne) and noncommunicable (mental, cardiovascular, allergic, etc.) conditions to an extent that living conditions become unbearable.²³ Third, melting glaciers can produce floods and even raise the sea level, forcing people living in the coastal areas to move internally. An example of such a situation is the expected migration from the coastal areas of Bangladesh as a consequence of the melting of the large Himalaya glaciers.²⁴ People may consider escaping a hostile environment in search of better living conditions for themselves and their families (environmental migrants), although migration itself may conversely affect health in a vicious circle.²⁵ According to the UCL-Lancet Commission on Migration and Health, climate changes are a major trigger for human mobility, possibly forcing as many as 200 million people to move from their place of residency by the year 2050,²⁶ even if factor-specific forecasts are difficult to perform, as many confounding social, economic, and political variables are likely to act in combination to drive environment-related migration. Further, the evidence that many individuals continue residing in hostile environments, possibly due to the lack of resources to move, makes the specific role of climate change in exclusively driving migration uncertain.²⁷

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2.1.5 LAND GRABBING. The intensive exploitation of rural areas in low-income countries, usually by international enterprises or even foreign governments, is referred to as land grabbing. Large areas are exploited to cultivate mainly biofuels or food crops or even to build large tourist resorts, with little (if any) economic benefit to the native communities and a negative impact on land impoverishment, agricultural biodiversity, and the local economy, adding to the consequences of climate changes.²⁸ Poor rural villagers, often devoid of land property documents, are obliged to leave their native areas with little compensation to move elsewhere in the country.²⁹ They often reach the degraded peripheries of the main cities, a setting that is largely hostile and different from the one their families have been living in for centuries, with physical and psychological detriments for them and their children.

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2.1.6 WARS, AUTHORITARIAN REGIMES, INSECURITY, AND DISCRIMINATION. According to the Uppsala Conflict Data Programme (UCDP) of the University of Uppsala, a major observatory of organized violence operating for over forty years, the number of wars or conflict outbreaks is on the rise.³⁰ In this time period, the number of non-state violent conflicts (n = 67) has surpassed the number of officially declared state violent conflicts (n = 54), making the recognition of asylum seekers difficult to ascertain under different national regulations. These bloody conflicts are happening in virtually all continents, offending civilians and denying civil and social rights to populations who are eventually forced to leave by dictatorships. The long-lasting wars in Syria and Afghanistan are forcing millions of individuals to leave their country of citizenship. Other conflicts taking place in the Horn of Africa (Eritrea, Somalia), Northern Africa (Libya), West Africa (Mali, Nigeria), and Latin America (Venezuela) are somehow undeclared but equally socially disrupting, denying basic human rights and access to quality education and a dignified life, especially for the fragile female population.³¹ It is to be noted that many people escaping conflicts and wars are relocated within national borders (as is the case for Yemen), thus they are not numbered in the international migrants count and instead are considered internal refugees.

3.0 Pull Macro-factors

3.1 Job Opportunities

The main pull factor for economic migrants is the prospect of labor in receiving countries, where there are low-skill job opportunities and higher salaries that may be partially returned to the origin families (remittances). This is not new; for example, Italian workers were incentivized by the Italian government to migrate from Southern Europe to the Central and Northern European Countries after the Second World War as a means to obtain return remittances and to prevent high internal unemployment.³² Migrants are often available to perform unattractive duties (such as agricultural or low-level services) that the nationals of destination countries are not willing to do anymore, mainly due to improved lifestyles and the aging of the population.

This may be viewed as a risk stratification strategy that makes migration a component of the economic perspective of the origin communities.³³ This remains true as long as the migrants reference group is the primary origin reference group, but it may change over time with better integration in the new society.

Of course, the economic attractiveness of a specific country or continent may vary over time and cycles are to be expected, as evidenced by the decreasing pulling economic strength of Southern Europe after the economic crisis that started in 2008.³⁴

3.2 Welfare Magnet

A precarious welfare state (lack of quality free education and accessible health systems) in the country of origin is an obvious push factor. However, it has been suggested that better service provisions may also be a push factor, as they provide people with a higher level of awareness and resources to migrate long distances.³⁵ On the other hand, the existence of a generous welfare state in the destination country is an attractive pull factor (the magnet hypothesis) that may discourage migrants from returning to their homeland. The cuts in welfare benefits offered in the