Media Releases

Childhood pre-migration health and circumstances shed light on the “healthy migrant effect”

March 16, 2016

Toron­to, ON — Stud­ies have shown that immi­grants to the U.S., Cana­da, and Aus­tralia tend to be health­i­er and live longer than non-immi­grants in their host coun­tries, once adjust­ments have been made for income and edu­ca­tion. There has been a great deal of spec­u­la­tion as to why this “healthy migrant effect” exists. One hypoth­e­sis pro­pos­es that it is due to self-selec­tion such that par­tic­u­lar­ly healthy indi­vid­u­als are more like­ly to choose to move to a dif­fer­ent coun­try, while those who are in poor health may be less will­ing or able to do so.

A study released today by the Uni­ver­si­ty of Toron­to and U.K.’s Med­ical Research Coun­cil (MRC) Unit for Life­long Health and Age­ing at UCL (LHA) found sup­port for this hypoth­e­sis using data from the MRC Nation­al Sur­vey of Health and Devel­op­ment (NSHD), a large nation­al­ly rep­re­sen­ta­tive lon­gi­tu­di­nal study of British chil­dren born in ear­ly March 1946 who have been sur­veyed more than twen­ty times over their life­time. The study, pub­lished online this week in the Cana­di­an Jour­nal of Pub­lic Health, com­pared the child­hood cir­cum­stances of 984 future emi­grants with 4378 non-emi­grants.

“The child­hood health of future migrants was much bet­ter than those who did not move to oth­er coun­tries,” says Pro­fes­sor Esme Fuller-Thom­son, San­dra Rot­man Endowed Chair at Uni­ver­si­ty of Toron­to’s Fac­tor-Inwen­tash Fac­ul­ty of Social Work and the Insti­tute for Life Course and Aging.

Researchers found that future emi­grants in the NSHD were less like­ly to have been born with a low birth-weight or to have a seri­ous ill­ness before the age of 5 and they were taller at age 6 (which reflects child­hood nutri­tion) than were the chil­dren who did not emi­grate.  It appears that fac­tors con­tribut­ing to pos­i­tive health selec­tion in migrant pop­u­la­tions begin as far back as child­hood.

“We also found that future emi­grants had supe­ri­or cog­ni­tive abil­i­ty at age 8 in com­par­i­son to their coun­ter­parts who stayed in Britain,” said co-author Sarah Bren­nen­stuhl of the Lawrence Bloomberg Fac­ul­ty of Nurs­ing at the Uni­ver­si­ty of Toron­to. “High­er cog­ni­tive abil­i­ty has been shown in oth­er stud­ies to be asso­ci­at­ed with bet­ter health in adult­hood and a low­er like­li­hood of devel­op­ing demen­tia in old age.”

Future emi­grants came from fam­i­lies with a high­er socioe­co­nom­ic posi­tion than those who remained per­ma­nent­ly in the UK. “They were more like­ly to have fathers who were pro­fes­sion­als, their moth­ers had a high­er lev­el of edu­ca­tion, their hous­ing qual­i­ty at age 4 was bet­ter, their par­ents showed more inter­est in the children’s school progress, and their par­ents were more like­ly to own their own home when the child was 6 years old” said Pro­fes­sor Diana Kuh, a co-author and Direc­tor of LHA and NSHD. “Child­hood socioe­co­nom­ic posi­tion has been shown in the NSHD and many oth­er stud­ies to be high­ly asso­ci­at­ed with adult health.”

“This study sup­ports the healthy migrant hypoth­e­sis for migra­tion between high-resource coun­tries,” said Pro­fes­sor Kuh.

A copy of the paper is avail­able to jour­nal­ists upon request. Please con­tact Uni­ver­si­ty of Toronto’s media rela­tions offi­cer, Dominic Ali at


Media con­tact:

Prof. Esme Fuller-Thom­son
Pro­fes­sor & San­dra Rot­man Endowed Chair
Fac­tor-Inwen­tash Fac­ul­ty of Social Work &
Insti­tute for Life Course & Aging
Uni­ver­si­ty of Toron­to
Cell: 416–209-3231

Dominic Ali
Media Rela­tions Offi­cer
Uni­ver­si­ty of Toron­to
Tel: 416–978-6974