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Keywords:

  • Child health;
  • overweight;
  • obesity;
  • transients and migrants

Summary

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conflict of Interest Statement
  8. References

To review the prevalence regarding overweight and obesity among children and adolescents from migrant and native origin within Europe, a systematic review (1999–2009) was performed, using Embase, PubMed and citation snowballing. Literature research resulted in 19 manuscripts, reporting studies in six countries, mostly situated in Western and Central Europe.

From this review, it appears that, in most of the European countries for which data are available, especially non-European migrant children are at higher risk for overweight and obesity than their native counterparts. The prevalence of overweight in migrant children ranged from 8.9% to 37.5% and from 8.8% to 27.3% in native children. The prevalence of obesity in migrant children ranged from 1.2% to 15.4% and from 0.6% to 11.6% in native children. Some limitations of the review are discussed, especially the problematic classification of migrant and native children.

Apparently, migrant children display an even more sedentary way of life or adverse dietary patterns, as compared with native children. To what degree these differences can be explained by socioeconomic and cultural factors remains to be investigated. As overweight and obese children are at risk for many chronic health problems, further research is urgently needed in order to develop preventive interventions.


Introduction

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conflict of Interest Statement
  8. References

Over the last decade, the prevalence of overweight and obesity among children and adults has risen in the Western world, also in Europe (1,2). Compared with the increasing overweight prevalence in adults, the international rise in overweight children even seems to have a faster rate (3,4).

Overweight and obesity are associated with various serious health consequences, such as cardiovascular disease, diabetes mellitus and cancer (5). With the obesity increase among children and adolescents, conditions that first were seen primarily in adults now are becoming more prevalent among younger people, such as insulin resistance, hypertension and hypercholesterolemia (6). Furthermore, child overweight affects self-esteem and influences the social and cognitive development of these children (7). Apart from these negative effects on health and quality of life, obesity appears to be responsible for a substantial economic burden in many European countries (8).

In general, obesity in childhood is a persisting health problem in adulthood. Already more than a decade ago, Dietz (9) argued that child obesity has a great chance of remaining at a later stage in life. Hence, the persistence of obesity from young ages emphasizes the importance of developing specific interventions at an early life phase to prevent long-term health damage in the future (10).

In the past 50 years, many European countries have shifted to immigrant societies. Because of the independence of former colonies, the educational opportunities and the need for cheap labour forces, sometimes combined with political reasons in the native country, several migration flows, towards and within Europe, took place. Therefore, European countries have experienced large changes in the composition of their populations (11).

Many migrants have ended up in disadvantaged positions with regard to their health (12). In particular, the risk of diabetes type 2 and coronary heart disease is elevated among certain migrant groups (13–15). Migration to Western societies seems to increase the risk of overweight and obesity (16), especially as a consequence of alterations in lifestyle. Migrants tend to engage in a more sedentary way of life, abandon their traditional food habits and adopt westernized dietary patterns (17–19). Additionally, migrants coming from less developed countries may entail pre-migration cultural preferences for larger body sizes, as these sizes are considered as signs of health and wealth (20–22). These body preferences may be easier to obtain within the new environment of affluence in the host countries.

A large amount of studies have been published on overweight and obesity, in relation to ethnicity and migration. In a review by Ogden et al. (23) for example, especially African–American and Mexican–American youth in the USA were at increased risk for overweight. No difference was made between more recent migrants and subjects, whose ancestors migrated. In contrast to traditional immigrant societies, such as the USA and Canada, large-scale migration to Europe is a post-second World War phenomenon. Consequently, migrant groups residing in these continents may be incomparable.

Study aim

Although overweight and obesity are important research topics worldwide, also in relation to ethnicity and migration, no previous systematic reviews have focused on differences in overweight and obese children and adolescents. Therefore, the aim of this review was to determine the prevalence regarding overweight and obesity among migrant children and adolescents, as compared with the native population within Europe.

Methods

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conflict of Interest Statement
  8. References

Search strategy

The terminology with respect to migrant and ethnic groups is controversial. Classification often reflects the migration history, the political climate concerning migration and integration and the legislation with regard to citizenship. These definition problems complicate a literature search. Therefore, a qualified librarian helped to design a comprehensive and sensitive search strategy.

Relevant literature was obtained from the following computerized databases: Embase and PubMed. Also, records were identified through citation snowballing. Searches were performed by using the official Medical Subject Headings (MeSH) or Subheadings (Sh). Entry terms were: overweight (MeSH) or obesity (MeSH); transients and migrants (MeSH), ethnic groups (MeSH) or ethnology (Sh); Europe (MeSH).

Although we wanted to involve only children and adolescents, defined as younger than 18 years old, the age of study participants was deliberately not specified in the search strategy. Because some research articles, which may not use children as entry term, do report on both children and adults, we did not want to exclude these studies a priori. Studies that did not report on children and/or adolescents separately were not included.

To ensure high sensitivity when retrieving studies, reference lists of all relevant identified articles were examined to discover other studies that were not indexed by the above databases. No language restrictions were imposed. All entry terms were ‘truncated’ and ‘exploded’ to cover as many articles as possible.

Inclusion and exclusion criteria

Manuscripts published between January 1999 and December 2009 were pre-selected in this review. Only articles that contained empirical studies regarding the prevalence of overweight and/or obesity according to migrant status were included. In order to allow for comparisons, data on the majority group had to be present.

Genetic biomedical literature was excluded, because these studies did not meet the aim of this review. Furthermore, editorials and position statements were not included. Also articles, in which cross-cultural comparisons between countries were conducted, were excluded. Equally excluded, were articles describing specific indigenous ethnic groups, which can not be considered as migrants (e.g. Sami) or as recent migrants (e.g. Roma). Finally, articles on adoptees or asylum seekers were not included.

Review procedures

This systematic review was performed in two stages. In the first selection phase, two independent reviewers evaluated each title and abstract applying the inclusion and exclusion criteria. Abstracts were excluded from further analysis if both reviewers agreed that they did not meet the criteria of this review. Studies that did not permit selection or rejection were considered after obtaining the full text. In the second selection phase, full-text articles of included abstracts were obtained and evaluated by both reviewers. Afterwards, Cohen's kappa was calculated to assess inter-rater agreement during the two phases. Disagreements about inclusion and exclusion were resolved by consensus. When several publications were written by the same (group of) author(s) on base of an identical research sample, the article, which described the results in most detail, was chosen.

Study comparisons

The Body Mass Index (BMI), calculated as weight in kilograms divided by the square of height in meters, was used to assess overweight and obesity. The International Obesity Task Force (IOTF) has developed an international reference standard to define overweight and obesity in children. This standard is based on pooled data from six national growth surveys: sex- and age-specific cut-off values (24).

Most studies included in this review make use of this IOTF classification. If not, this is indicated in the overview table (see Results section). Some studies applied both the IOTF cut-off points and locally determined cut-off points. In that case, only IOTF results have been included in this review, in order to be comparable with the data from the other studies. In most studies, overweight included obesity. When overweight percentages did not include obesity, overweight percentages, including obesity, were calculated by the first author.

Results

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conflict of Interest Statement
  8. References

Results of our literature search are presented in Fig. 1. After correcting for duplicates, we identified 684 articles using our search criteria.

image

Figure 1. Flow chart of search results.

Download figure to PowerPoint

Based on the information contained within article abstracts, 617 articles were excluded for not meeting the inclusion criteria. Cohen's kappa for stage one of the search was 0.85, which can be regarded as high (92% agreement). A further 48 articles were rejected in stage two of the search, based on a review of the full-text manuscripts by two reviewers. This resulted in 19 manuscripts being retained for evaluation. Inter-rater reliability for stage two of the search was good (Cohen's kappa 0.76; 89% agreement).

The main results of our review are summarized in Table 1. For each manuscript, besides the country name (column 1), the surname of the first author and relevant years (column 2), the study location, the study setting and the included age group(s) are presented in column 3. Information on study type, sample size and sampling method is displayed in column 4. Column 5 summarizes the main aim(s) of each study. Most studies had a purely descriptive aim. Studies were considered as descriptive when their aim was to present data on overweight and obesity, according to basic characteristics, such as age, sex and migrant background. These studies did not intend to explain differences between native and non-native children, even when data on socioeconomic position were available. In addition, trend studies, aiming to show differences in time, were also categorized as descriptive. Moreover, most of these studies did not provide longitudinal data according to migrant status. Therefore, we ultimately extracted cross-sectional data from these studies. Column 6 informs about the applied BMI cut-off classification system. As mentioned before, usually the IOTF standard has been used. However, exceptions are mentioned in this column. In column 7, definitions and criteria, according to which the migrant and ethnic groups have been defined and categorized, are described. Column 8 provides information on the analysis: (i) whether differences between migrant and native groups have been tested and (ii) whether overweight and obesity figures have been adjusted for differences in socioeconomic status. Finally, column 9 shows the migrant and ethnic groups for which data on overweight and obesity are presented in columns 10 and 11.

Table 1.  Overview results European literature (1999–2009)
1234567891011
CountrySurname first author (date of fieldwork, date of publication)a. Study location b. Study setting c. Age group(s)a. Study type b. Sample size c. Sampling methodMain study aim(s)BMI cut-off classification systemDefinition or criteria regarding migrant and ethnic group(s)a. Differences between migrants and natives tested? b. Differences in socioeconomic position adjusted?Migrant and ethnic group(s)Overweight, including obesity, % (95% CI)Obesity, % (95% CI)
OverallBoysGirlsOverallBoysGirls
  • *

    95% CI unknown.

  • only overall testing.

  • P < 0.05.

  • BMI, body mass index; CI, confidence interval; na, not applicable.

DenmarkAarup (2002, 2003, 2008) (25)a. City (Aalborg)a. Cross-sectional b. 825 c. AllDescriptive, including attitudes of parents towards treatmentInternational Obesity Task ForceClassified into two pre-defined categories (on base of full name)a. YesDanes (n = 802)7.1*nana2.1*nana
b. The municipality of Aalborgb. NoOther ethnic background (n = 23)17.4*,‡nana8.7*nana
c. 3 years
Billeskov (1999–2005) (26)a. City (Ishøj) b. The municipality of Ishøj c. 6–16 yearsa. Longitudinal (trend) b. 2550 c. AllDescriptiveNational BMIClassified into two pre-defined categories (on base of mother tongue)a. NoDanes (n = na)8.4*nanananana
b. NoChildren speaking two languages (n = na)18.6*nanananana
UKBalakrishnan (1991–1999, 2008) (27)a. District (East Birkshire) b. Existing dataset (Child Health Information System) c. 5–7 yearsa. Longitudinal (trend) b. 29 641 c. AllDescriptiveNational BMINo informationa. Only testing of differences for boys and girls separately b. NoWhite (n = 13 116)20.720.121.39.79.79.7
(20.0–21.4)(19.2–21.1)(20.3–22.3)(9.2–10.2)(9.0–10.5)(9.0–10.5)
Afro-Caribbean (n = 223)24.725.224.110.811.310.2
(19.2–30.9)(17.6–34.2)(16.4–33.3)(7.0–15.6)(6.2–18.6)(5.2–17.5)
South Asian (n = 3025)25.030.918.913.66.011.1
(23.5–26.6)(28.6–33.3)(16.9–21.0)(12.4–14.8)(4.2–17.9)(9.5–12.8)
Duncan (na, 2006) (28)a. City (Birmingham) b. Six Secondary schools c. 11–14 yearsa. Cross-sectional b. 276 c. StratifiedDescriptive, including relationships with body satisfaction, body fat and physical activityInternational Obesity Task ForceClassified into two pre-defined categories (on base of categorization Department for Education and Skills)a. No b. NoWhite (n = 176)26.0*nana4.8*nana
Black (n = 33) 23.5*nana8.8*nana
 Harding (2002, 2003, 2008) (29)a. City (London) b. 51 secondary schools c. 11–13 years c. Randoma. Cross-sectional b. 6407 c. RandomExplanatory, including impact of overweight on blood pressure, in relation to ethnicityInternational Obesity Task ForceSelf-reported ethnicity in seven pre-defined categoriesa. Yes b. NoWhite UK (n = 629)na19.7 (16.6–22.8)20.2 (16.9–23.5)na6.4 (4.4–8.3)6.6 (4.6–8.6)
White other (n = 392)na23.0 (18.8–27.1)20.6 (16.0–25.1)na9.2 (6.3–12.1)7.2 (4.3–10.1)
Black-Caribbean (n = 474)na15.4 (12.1–18.7)28.1 (23.9–32.4)na10.3 (7.6–13.1)12.6 (9.5–15.7)
Black-African (n = 487)na17.5 (14.1–20.8)27.9 (24.2–31.5)na8.2 (5.8–10.7)9.9 (7.4–12.3)
Indian (n = 265)na18.5 (13.8–23.2)20.8 (15.3–26.3)na6.8 (3.7–9.8)4.2 (1.5–7.0)
Pakastani/Bangladeshi (n = 393)na19.6 (15.7–23.5)17.9 (12.8–23.0)na8.4 (5.6–11.2)4.1 (1.5–6.8)
Mixed (n = 280)na21.4 (16.6–26.3)25.3 (20.1–30.5)na8.2 (5.0–11.5)8.9 (5.5–12.4)
Hughes (2005, 2007) (30)a. City (Glasgow) b. Seven primary schools c. 4–12 yearsa. Cross-sectional b. 1548 c. AllDescriptive, including a process evaluation of an interventionNational BMINo informationa. Yes b. NoWhite (n = 918)31.0*nana17.0*nana
Black/ethnic minority (n = 630) 32.0*nana22.0*,‡nana
Jebb (1997, 2004) (31)a. Country (UK) b. Existing dataset (National Diet and Nutrition Survey) c. 4–17 yearsa. Cross-sectional b. 1836 c. RandomDescriptiveInternational Obesity Task ForceNo informationa. Yes b. NoWhite (n = 1667)18.9*nana3.5*nana
Afro-Caribbean (n = 47)23.4*,‡nanananana
Asian (n = 81) 25.9*,‡nana13.6*,‡nana
 Saxena (1999, 2004) (32)a. Non-sovereign country (England) b. Existing dataset (Health Survey for England) c. 2–20 yearsa. Cross-sectional b. 5869 c. RandomDescriptiveInternational Obesity Task ForceSelf-reported ethnicity in seven pre-defined categoriesa. Only overall testing of differences b. NoGeneral (n = 1866)na21.7*,†22.3*,†na5.8*,†5.8*,†
Afro-Caribbean (n = 695)na22.6*33.3*,‡na5.1*13.0*,‡
Indian (n = 571)na29.6*,‡24.0*na7.9*2.1*,‡
Pakistani (n = 894)na26.2*,‡25.7*na9.0*8.0*,‡
Bangladeshi (n = 712)na14.2*,‡20.7*na2.8*,‡5.8*
Chinese (n = 310)na14.4*,‡13.0*,‡na4.7*1.2*,‡
Irish (n = 641)na17.3*25.6*na3.3*8.3*
Wardle (1999, 2006) (33)a. City (London) b. 36 secondary schools c. 11–16 yearsa. Longitudinal (trend) b. 5863 c. RandomDescriptiveInternational Obesity Task ForceSelf-reported ethnicity in four pre-defined categoriesa. Yes b. YesWhite (n = 2607)nana28.0*,‡nanana
Black and mixed black (n = 1036)nana38.2*,nanana
Asian and mixed Asian (n = 428)nana19.8*,nanana
Other/mixed ethnic groups (n = 198)nananananana
the Netherlandsde Wilde (1999–2007, 2009) (34)a. City (The Hague) b. Existing dataset (Child Health Care Assessments) c. 3–10 and 13–16 yearsa. Longitudinal (trend) b. 85 234 c. AllDescriptiveInternational Obesity Task ForceClassified into four pre-defined categories (on base of Dutch Statistics classification)a. No b. No 3–6 years3–6 years3–6 years3–6 years3–6 years3–6 years
Dutch (n = 34 009)na9.0*12.9*na1.8*3.0*
Turkish (n = 9219)na23.4*25.4*na9.5*8.1*
Moroccan (n = 7165)na17.4*24.0*na5.5*6.6*
Surinamese South Asian (n = 6043)na8.9*10.0*na3.3*2.5*
 7–10 years7–10 years7–10 years7–10 years7–10 years7–10 years
Dutch (n = 11 193)na15.5*20.0*na3.6*4.3*
Turkish (n = 3354)na35.6*37.5*na11.6*10.8*
Moroccan (n = 2509)na24.8*30.6*na7.3*8.6*
Surinamese South Asian (n = 2301)na26.0*25.5*na9.4*6.3*
         13–16 years13–16 years13–16 years13–16 years13–16 years13–16 years
Dutch (n = 5191)na18.1*18.4*na3.7*3.7*
Turkish (n = 1598)na34.7*31.5*na9.3*8.3*
Moroccan (n = 1323)na23.1*29.8*na6.9*6.3*
Surinamese South Asian (n = 1329)na24.7*18.7*na7.9*4.9*
Fredriks (1996, 1997, 2005) (35)a. Cities (Amsterdam, Rotterdam, Utrecht, The Hague) b. Existing dataset (Fourth Dutch Growth Study c. 0–21 yearsa. Cross-sectional b. 20 259 c. AllDescriptiveInternational Obesity Task ForceClassified into four pre-defined categories (on base of birth country of both parents)a. No b. NoDutch in large cities (n = na)na12.6*16.5*na1.6*2.8*
Dutch in other than large cities (n = na)na8.7*11.3*na0.8*1.4*
Turkish (n = 2904)na23.4*30.2*na5.2*7.2*
Moroccan (n = 2855) na15.8*24.5*na3.1*5.4*
Snoek (2003, 2007) (36)a. Regions (North, South, East, West) b. 55 secondary schools c. 11–16 yearsa. Cross-sectional b. 10 087 c. RandomDescriptive, including association between overweight, eating behavior, and health-related lifestyle factorsInternational Obesity Task ForceClassified into five pre-defined categories (on base of Dutch Statistics classification)a. Only overall testing of differences b. NoDutch (n = 7239na10.2*,†6.4*,†na0.8*,†0.6*,†
Surinam/Antillean (n = 319)na9.5*13.2*na0.0*2.2*
Moroccan (n = 90)na9.1*10.9*na0.0*2.2*
Turkish (n = 298)na18.7*15.4*na1.9*2.8*
Other (n = 883)na15.1*7.6*na1.7*0.8*
van der Horst (2005, 2006, 2009) (37)a. City (Rotterdam) b. 17 secondary schools c. 12–15 yearsa. Cross-sectional b. 1206 c. StratifiedDescriptiveInternational Obesity Task ForceClassified into two pre-defined categories (on base of Dutch Statistics classification)a. No b. NoWestern (n = 597)20.0nanananana
Non-Western (n = 609) 21.4nanananana
GreeceHassapidou (2006, 2009) (38)a. City (Thessaloniki) b. 7 schools c. 8–12 yearsa. Cross-sectional b. 266 c. StratifiedDescriptiveInternational Obesity Task ForceNo informationa. Yes b. NoGreek (n = 236)25.8*nana12.7*nana
Immigrant (n = 30) 10.0*,‡nana3.3*,‡nana
GermanyKalies (1997, 2002) (39)a. District (Bavaria) b. Existing dataset (School Entry Examination) c. 5–6 yearsa. Longitudinal (trend) b. 127 735 c. AllDescriptiveInternational Obesity Task ForceClassified into two pre-defined categories (on base of nationality of the child)a. Yes b. No 5 years5 years5 years5 years5 years5 years
German (n = 14 472)na8.8 (8.3–9.3)11.9 (11.4–12.4)na2.7 (2.5–3.0)3.1 (2.8–3.4)
Non-German (n = 1191)na16.5 (14.4–18.7)16.5 (14.4–18.8)na6.8 (5.4–8.4)5.6 (4.3–7.1)
 6 years6 years6 years6 years6 years6 years
German (n = 45 463)na9.3 (9.0–9.6)11.8 (11.8–12.1)na2.6 (2.4–2.7)3.0 (2.8–3.2)
Non-German (n = 4371)na16.8 (15.7–17.9)18.5 (17.3–19.8)na5.9 (5.2–6.7)5.8 (5.1–6.6)
Koller (2004, 2009) (40)a. City (Munich) b. Existing dataset (School Entry Examination) c. naa. Cross-sectional b. 9353Descriptive, including participation in vaccination and health check-upsNational BMIClassified into two pre-defined categories (on base of mother tongue)a. Yes b. NoGerman (n = 384)6.7*nanananana
Other (n = 513) 17.3*,‡nanananana
Kuepper-Nybelen (2001, 2002, 2005) (41)a. City (Aachen) b. Existing dataset (School Entry Examination) c. 5–6 yearsa. Cross-sectional b. 1979 c. AllDescriptive, including additional analysis of risk factorsInternational Obesity Task ForceClassified into two pre-defined categories (on base of nationality of the mother)a. No b. NoGerman (n = 1522)10.6*nanananana
Other (n = 452) 19.3*nanananana
Will (2002, 2005) (42)a. City (Bielefeld) b. 12 primary schools c. 6–7 yearsa. Cross-sectional b. 525 c. AllDescriptive, including additional analysis within migrantsInternational Obesity Task ForceClassified into two pre-defined categories (on base of birth country of both parents)a. Yes b. NoGerman (n = 265)9.1 (5.6–12.5)7.6 (3.3–11.9)10.8 (5.3–16.4)1.9 (0.2–3.5)0.7 (−0.7–2.0)3.3 (0.1–6.5)
Migrant (n = 258)14.7 (10.4–19.1)10.1 (4.9–15.3)19.4 (12.6–26.2)3.1 (1.0–5.2)1.6 (−0.6–3.7)4.7 (1.0–18.3)
AustriaKirchengast (na, 2006) (43)a. City (Vienna) b. 46 primary schools c. 6, 10 and 15 yearsa. Longitudinal b. 1786 c. RandomDescriptiveNational BMIClassified into three pre-defined categories (on base of birth country of both parents)a. Yes, but unclear (no results for each migrant group) b. No 6 years6 years6 years6 years6 years6 years
Austrian (n = 794)na17.8*17.9*na9.4*7.6*
Turkish (n = 437)na20.6*20.3*na10.3*8.8*
Former Yugoslavian (n = 555)na23.1*25.6*,‡na10.3*14.3*
 10 years10 years10 years10 years10 years10 years
Austrian (n = 794)na27.3*24.8*na11.6*9.4*
Turkish (n = 437)na20.9*27.7*na7.9*12.5*
Former Yugoslavian (n = 555)na36.7*,‡30.8*na9.2*15.4*
 15 years15 years15 years15 years15 years15 years
Austrian (n = 794)na23.1*24.2*na11.3*8.4*
Turkish (n = 437)na25.0*29.2*na8.9*12.8*
Former Yugoslavian (n = 555)na28.0*27.6*na9.2*12.6*

Overall, with the exception of Greece, only studies from Western and Central European countries were available (see column 1). Most studies investigated migrants coming from overseas. Migrants within Europe were seldom studied (see column 9).

In one English study (32), it was not possible to exclude adolescents above the age of 18 (see column 3). We did not exclude these results, as this age group was rather small, as compared with the younger children and adolescents.

Our search procedure resulted in the inclusion of manuscripts using very divergent criteria to define migrant populations (see column 7). In some studies, neither any definition nor any criteria to delineate migrant from native children was given.

Studies based their percentages of overweight and obese children upon measurements by trained raters. Only in one Danish and one Dutch study, data were based on reports by the parents (25) or self-reports (37). In this particular Dutch study, the percentages of overweight and obese children are considerably lower in this study than in the other – even the other Dutch – included studies. Apart from that, there was no large difference between the two included Danish studies.

Leaving these two studies out of consideration, the prevalence of overweight in migrant boys ranged from 8.9% (3–6 years old Surinamese South Asian in the Netherlands) to 35.6% (7–10 years old Turkish in the Netherlands), and in migrant girls from 10.0% (3–6 years old Surinamese South Asian in the Netherlands) to 37.5% (7–10 years old Turkish in the Netherlands). In the natives, the prevalence of overweight in boys ranged from 8.8% (5–6 years old in Germany) to 27.3% (10 years old in Austria), and in native girls from 11.8% (6 years old in Germany) to 24.8% (10 years old in Austria).

Further, the prevalence of obesity in migrant boys ranged from 2.8% (2–20 years old Bangladeshi in the UK) to 11.6% (7–10 years old Turkish in the Netherlands), and in migrant girls from 1.2% (2–20 years old Chinese in the UK) to 15.4% (10 years old former Yugoslavians in Austria). In the natives, the prevalence of obesity in boys ranged from 0.7% (6–7 years old in Germany) to 11.6% (10 years old in Austria), and in native girls from 0.6% (11–16 years old in the Netherlands) to 9.7% (5–7 years old in the UK).

Although differences were not always statistically significant, most studies do indicate an elevated risk on overweight and obesity among migrant populations. In the UK, some exceptions could be noticed: lower percentages of overweight in both Chinese and Bangladeshi boys and in Chinese girls, as well as lower percentages of obese in both Bangladeshi boys and in Chinese and Indian girls. This opposite pattern is also found in Greece, where migrant children are less likely to suffer from overweight and obesity.

Turkish children seem to be the group most at risk. The percentages overweight and obesity in Turkish children were highest in the Netherlands, Germany and Austria.

Discussion

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conflict of Interest Statement
  8. References

Conclusions

The prevalence of overweight in migrant children ranged from 8.9% to 37.5% and from 8.8% to 27.3% in native children. The prevalence of obesity in migrant children ranged from 1.2% to 15.4% and from 0.6% to 11.6% in native children. Overall, we may conclude that migrant children are at increased risk for overweight and obesity, as compared with native children. There were slight differences in overweight between boys and girls, in favour of the boys (lower BMI scores). American data point into the same direction, although European migration history is more recent than in the USA (23).

It is important to point out that overweight and obesity also increase rapidly in many non-Western and developing countries. Already in 2000, de Onis and Blössner (44) noticed a most marked increase in the Northern African countries, such as Morocco, and in some countries in South Africa. In the countries of origin, prevalence of overweight and obesity among these children reaches the level of native children in Europe. In a study by Pirinçci et al. (45) among 6–11 years old children in an Eastern Turkish city, 14.8% was overweight, of which 1.6% obese. Data for 6–16 years old children in a Western Turkish city were similar: 15.9% was overweight, of which 3.7% obese. Similarly studies in Indian cities found an overweight prevalence of 16%, including obesity, in 13–18 years urban children (46). This also applies to Pakistan where the prevalence of overweight was 14%, including obesity, in Karachi (47). However, comparing these figures with those of the migrant children originating from these countries in Europe makes clear that overweight and obesity were even more prevalent among the latter. Data from Surinamese South Asian children (48), aged 12–17 years, show a somewhat lower prevalence of overweight among girls, as compared with their counterparts in the Netherlands (13.6% vs. 17.1%), but a somewhat higher prevalence of overweight among boys (24.4% vs. 19.9%).

Physical exercise and dietary patterns are principal causes of overweight and obesity, but it remains unclear how this increased risk of overweight and obesity in many migrant groups can be explained. Indeed, migration may entail a more sedentary lifestyle and other nutritional habits (17–19). Although this may explain an increase in risk when migrating, it does not account for a higher risk in migrants, as compared with native children.

Limitations

Most studies included in this review did not allow assessing to what degree ethnic differences could be explained by socioeconomic factors. Also, the interaction between migrant background and socioeconomic position needs consideration. In developed countries overweight and obesity are more prevalent among children in lower socioeconomic strata, whereas in developing countries the opposite is true. The majority of the studies only presented non-adjusted data, even those that had information on socioeconomic position at their disposition. However, the study by Kuepper-Nybelen et al. (41) showed that educational level of the mother explains much of the differences between the two groups of children. Furthermore, the study by Will et al. (42) indicated that in German children overweight is most prevalent in families with a low socioeconomic status, whereas in non-German children the reverse is true. Apart from that, none of the studies included took differences in generational status into consideration, although data in some of the Dutch studies might have allowed such analyses. Additionally, only one study investigated length of stay: the study by Will et al. (42) associated migration duration with overweight in migrant children.

The 19 studies in this review cover only six European countries, all but one situated in Western and Central Europe. Although we did not include language limitations in our search, no information was available for countries, which have a longer immigration history, such as Sweden, Norway and Belgium. This also applies to most Southern European countries, such as Italy, Spain and Portugal, which are more recent immigrant societies, as compared with Northern and Western European countries (11). The prevalence of overweight and obesity in native children is high in Greece, as appeared in our review. These Greek results are contrasting with those from all other studies. This finding probably can be explained by the fact that Greece attracted migrants more recently than the other countries included in this review. Therefore, most migrants are first generation. It can be expected that this also applies to other countries in Southern Europe. As a consequence, including more of these countries might change the overall conclusion of increased risk of overweight and obesity in migrant children.

Furthermore, the classification of children as migrant or native is problematic, because different criteria have been applied making comparisons between countries difficult. In three out of seven studies from the UK, no information at all is provided on how migrant status was defined. In three studies, self-reported ethnicity was used. As a result, the ethnic groups may include both recent migrants and descendants from migrants in previous generations. On the contrary, some studies on the European continent use a more direct indicator of migrant status by applying country of birth as criterion. This indicator has the advantage of being objective and stable, better allowing for comparisons over time and between studies (49). However, this is only the case when an indicator is applied uniformly in all studies, which does not seem the case. For example, most Dutch studies consider children as migrants when at least one parent is born abroad, thus including both first and second generation migrants, whereas studies from other countries only apply country of birth of the child. Apart from that, more indirect indicators have been used, such as full name, mother tongue or nationality. These indicators have limited value, because migrants may have double nationality. Besides, it hinders comparisons between countries, as there may be differences between countries in the possibilities to adopt the nationality of the receiving country. A final remark in this respect concerns the use of the seemingly simple and straightforward distinction between native and non-native, masking the diversity within migrant groups. For example, in most studies migrants of Asian or African descent are grouped into a few categories without further description. This incomparability may be part of the explanation why even within one country, in this case the UK, it remains unclear which groups are more at risk: migrants with a South Asian or with an African descent. Indeed, as appeared from the study by Saxena et al. (32), distinguishing between Pakistani, Bangladeshi and Indian migrant children makes differences between these groups visible. In this review, differences concerning Black-Caribbean and Black-African children are small. Overall, notwithstanding these classification problems, this review provides evidence that, at least in Western Europe, migrant children are at increased risk for overweight and obesity.

Next, the included studies in this review cover a wide age range comprising children from the age of 2 until adolescents of 18 and even 20. Depending on the study, sometimes broad and sometimes limited age ranges are included, again making comparisons difficult. Nevertheless, it appeared that, irrespective of age, migrant children are generally at increased risk for overweight and obesity.

Furthermore, differences in response rates between native and migrant children may lead to bias, at least when these rates are influenced by overweight and obesity. Unfortunately, we were not able to assess this possible source of bias. Part of the studies included BMI measurements, collected during health examinations in school or at school entry. Although the articles are not completely clear on this matter, we have the strong impression that these examinations are obligatory. In the Netherlands, Child Health Care authorities have information on almost all children. Some of the studies included in this review are based on these data. In the case of health surveys, the authors often did not mention response rates, or, if they did, they did not provide separate data, in relation to ethnicity and migration. In these cases, response is not an issue.

As a final limitation, we used the IOTF cut-off points if available in this review. The use of this classification system sometimes is subject to criticism, because it is based on data from only six countries. However, applying references of the receiving or the home countries is also questionable, as they disregard either possible genetic factors or changes in lifestyle related to migration.

From this review, it appears that in most of the European countries for which data are available, especially non-European migrant children are at higher risk for overweight and obesity than their native counterparts. As overweight and obese children are at risk for many chronic health problems, prevention is urgently needed. However, little is known why these children are at an even higher risk than native children. So, future research needs to investigate why these children apparently display an even more sedentary way of life or adverse dietary patterns, as compared with their native counterparts, in order to initiate effective prevention and intervention activities in these specific migrant and ethnic groups. Not only socioeconomic disadvantage, generational status and length of stay should be taken into account, but also cultural factors, such as specific exercise and food habits, combined with parental factors. This is especially important in children and adolescents, as they constitute a major part of the migrant populations in Europe.

Conflict of Interest Statement

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conflict of Interest Statement
  8. References

No conflict of interest was declared.

References

  1. Top of page
  2. Summary
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Conflict of Interest Statement
  8. References
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