Are height and leg length universal markers of childhood conditions? The Guangzhou Biobank cohort study.
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.


METHODS
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.


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.
Schooling
C M
CM
Department of Community Medicine and School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
Jiang
C Q
CQ
Heys
M
M
Zhang
W S
WS
Adab
Peymane
P
Cheng
K K
KK
Lam
T H
TH
Leung
G M
GM
D000368:Aged; D000369:Aged, 80 and over; D001827:Body Height; D002648:Child; D002657:Child Development; D002681:China; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007866:Leg / Q000033:anatomy & histology* / Q000254:growth & development; D008297:Male; D008572:Menarche; D008875:Middle Aged; D012307:Risk Factors; D012923:Social Class; D012924:Social Conditions / Q000706:statistics & numerical data*