Both childhood and adult socioeconomic position (SEP) continue to be associated with adult body mass index (BMI) in Britain despite policies designed to reduce BMI inequalities, according to a study published in PLOS Medicine by David Bann, from the UCL Institute of Education, UK, and colleagues.
Previous studies have found that lower SEP is associated with higher adult BMI, but whether those associations have changed over the past decades was unclear. In the new study, researchers examined data on 22,810 people enrolled in three British birth cohort studies: the 1946 MRC National Survey of Health and Development, including people aged 20 to 64; the 1958 National Child Development Study, including people aged 23 to 50; and the 1970 British Birth Cohort Study, including people aged 26 to 42. Data were collected on each person's SEP as a child (based on father's occupation) and adult (based on own occupation), and on their BMI throughout adulthood.
Lower SEP in childhood was associated with higher adult BMI in both genders and in all cohorts. This association increased with age--the older someone got, the greater the influence of childhood SEP on BMI. The association between adult SEP and BMI was generally stronger in women than men and in more recent years, although not as individual people aged. For example, among those born in 1946, 42-43 year-old women in the lowest SEP group (unskilled occupations) had a BMI 2.0 kg/m2 higher than those in the highest SEP group (professional occupations); among those born in 1970 that difference had grown to 3.9 kg/m2.
"The persistence of inequalities in BMI throughout adulthood across different generations suggests that new and/or improved strategies are required to reduce them," the authors say. "Given our findings of progressively widening BMI inequalities across adulthood, and the fact that BMI tends to track across life, interventions may be most effective when initiated as early in life as possible."
This project is part of a collaborative research programme entitled 'Cohorts and Longitudinal Studies Enhancement Resources' (CLOSER). This programme is funded by the ESRC grant reference: ES/K000357/1. The UK Medical Research Council provides core funding for the MRC National Survey of Health and Development and RH and DK (MC_UU_12019/1, MC_UU_12019/2). The UK Economic and Social Research Council provides core funding for the National Child Development Study and the British Cohort Study (ES/M001660/1). DB is partly funded by the ESRC (grant reference ES/M008584/1), but has no involvement in funding decisions from ESRC. RH and DK work at the MRC Unit for Lifelong Health and Ageing at UCL but have no involvement in funding decisions for the MRC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
The authors have declared that no competing interests exist.
Bann D, Johnson W, Li L, Kuh D, Hardy R (2016) Socioeconomic Inequalities in Body Mass Index across Adulthood: Coordinated Analyses of Individual Participant Data from Three British Birth Cohort Studies Initiated in 1946, 1958 and 1970. PLoS Med 13(12): e1002214. doi:10.1371/journal.pmed.1002214
Centre for Longitudinal Studies, UCL Institute of Education, London, United Kingdom
School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom
Population, Policy and Practice, UCL Institute of Child Health, London, United Kingdom
MRC Unit for Lifelong Health and Ageing at UCL, London, United Kingdom
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