Social environment and height: England and Scotland

This study was designed to investigate the social characteristics associated with the height of primary schoolchildren aged from 5 to 11. Data were analysed for 8491 representative sample children measured in England and Scotland in 1987 and 1988 and 3203 inner city children measured in England in 1987. Height was negatively associated with social class but the association was not significant after allowing for biological variables. A negative gradient of height with size of sibship was evident in white children but was less so in AfroCaribbean and Asian children. The individual associations of 11 different environmental characteristics were examined after allowing for biological factors and size of sibship. Consistent associations with height included a negative gradient of height with increasing latitude and an association of taller stature with increasing maternal age. A social class gradient in height is accounted for by associations with biological factors, particularly the parental heights; environmental attributes are weakly associated with height after allowing for biological factors. Department of Public Health Medicine, United Medical and Dental Schools, St Thomas's Campus, London SEI 7EH M C Gulliford S Chinn R J Rona Correspondence to: Dr Gulliford. Accepted 15 August 1990 Children's height is a sensitive indicator of their physical wellbeing, and has been recommended as a measure of their nutritional state.' Associations between height and environmental characteristics have been investigated as possible indications of adverse influences on growth. In such investigations a number of variables including the paternal social class2-7 and employment,5 the family size,4 5 the number of parents at home,8 and the presence of overcrowding8 have been used to characterise social conditions during childhood.2 A gradient associating height with social class has been documented both in adults3 and children,4-7 but the existence of a gradient does not itself indicate a direct influence on growth. An association between height and a given social characteristic is difficult to interpret because of the number of confounding variables among the social characteristics of the child's environment and between social and biological factors. It is necessary to adjust for confounding variables with multiple regression analysis but this raises the question: what confounding variables should be allowed for in such analyses? The National Study of Health and Growth is a surveillance study which was set up in 1971 to monitor the growth of primary schoolchildren in England and Scotland.9 In 1983 a second (inner city) sample was recruited.8 Reports from this study have shown associations between height and a number of characteristics of the social environment including paternal social class and employment,5 8 type of school meals,'0 presence of overcrowding in the home, and the educational attainment of the mother.8 The selection of variables for inclusion in these analyses has, however, been inconsistent. We therefore undertook the present analyses to examine the problem of confounding variables in more detail. We aimed to define the variables that should be included in analyses and to re-examine the association between children's height and paternal social class for children living in England and Scotland in 1987 and 1988. Subjects and methods