Are height and leg length universal markers of childhood conditions? The Guangzhou Biobank cohort study
- 1Department of Community Medicine, and School of Public Health, The University of Hong Kong, Hong Kong SAR, China
- 2Guangzhou Occupational Diseases Prevention and Treatment Centre, Guangzhou Number 12 Hospital, Guangzhou, China
- 3Department of Public Health and Epidemiology, University of Birmingham, UK
- Professor T H Lam, Department of Community Medicine and School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong SAR, China;
- Accepted 18 September 2007
Objective: In developed western populations longer legs have been shown to be a marker of better early childhood conditions. In the first generations to experience the epidemiologic transition and associated economic development, epigenetic constraints on growth might preclude improved childhood conditions from increasing leg growth or height.
Design, setting and participants: Multivariable linear regression was used to assess the association of parental growth environment, proxied by parental literacy, and childhood conditions, proxied by parental possessions, with leg length, sitting height and height in a cross-sectional sample from 2005–6 of 9998 Chinese people aged at least 50 years from phase 2 of the Guangzhou Biobank Cohort Study.
Main results: Adjusted for age and sex, the association of childhood conditions with leg length and height varied with parental literacy (interaction p values <0.01 and 0.03), but not for sitting height (p value 0.43), with statistically significant trends (p values <0.01) for parental possessions to be associated with longer legs and greater height only in the offspring of two literate parents where legs were longer by 0.56 cm (95% CI 0.27 to 0.86) and height greater by 1.16 cm (95% CI 0.74 to 1.58) for participants with most, compared with least, parental possessions in childhood.
Conclusions: Epigenetic influences originating in earlier generations may constrain growth during the infancy and/or childhood phases in very recently developed populations. Neither height nor leg length should be assumed to be consistent proxies of early life environment with corresponding implications for economic history, the aetiology of some chronic diseases and the monitoring of population health.
Funding: The study was funded by The University of Hong Kong Foundation for Development and Research, and the University of Hong Kong University Research Committee Strategic Research Theme Public Health, Hong Kong; Guangzhou Public Health Bureau, and Guangzhou Science and Technology Bureau, Guangzhou, China; and The University of Birmingham, UK. The funding sources had no role in any of the following: study design; the collection, analysis, and interpretation of data; the writing of the report; and the decision to submit the paper for publication.
Competing interests: None.