Blood pressure and migration in children.

The effect of migration on childhood blood pressure levels has been studied by comparing children before and after migration to New Zealand with children who stayed at home on the Pacific atolls of Tokelau. Data were collected in 1971 on 502 children (97% response rate) aged 5--14 years resident in Tokelau and follow-up data were collected in New Zealand and in Tokelau in 1975--1977 (respknse rate 91%). No selection factors were detected before migration. After migration, the younger migrants had significantly higher blood pressures and were heavier, but not taller, than the non-migrants. Weight differences explained some but not all of the blood pressure differences. There were no differences in body size between the 2 groups of older children although the older non migrant girls had higher blood pressure than the migrant girls.