Association between height at age 2 years and adolescence school performance: evidence from Birth to Twenty Cohort Study
Date
2011-03-25
Authors
Nkomo, Palesa Manthabiseng
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Abstract
Background
The first two years of a child’s life are crucial for cognitive development. In
societies where there are high rates of poverty, children are at risk of undernutrition
and subsequently stunting. Insufficient nutrition in early childhood results
in growth retardation in young infants and subsequently weak school
performance later in life due to poorer cognitive development. As far as we know
no study has been conducted in South Africa to examine the association
between height at age 2 years and school performance at the end of primary
school.
Purpose
The primary objective of this study was to investigate the association between
growth at age 2 years and education performance (school performance in
Mathematics and English or first language) of adolescents at the end of primary
school (grade 7). In addition, other growth variables such as weight-for-age, BMIfor-
age and weight-for-height were tested for the association as a secondary
objective. Prevalence of stunting, underweight, wasting and obesity at age two
years was also investigated.
Methods
This study is a primary analysis of historical data collected from Birth to Twenty
(BT20) cohort in Johannesburg, South Africa. A cohort study conceptualised to
v
investigate the effects of the urbanization and societal transition on health and
development A longitudinal study design within the BT20 cohort was employed.
A total of 252 study participants were included in the study.
An ordinal logistic model was used to test for association between growth at age
two years and school performance. Potential confounders such as maternal
education, birth weight and socio-economic status as defined by household
assets were adjusted for in the model.
Results
At age two years, about 29% of the study participants were stunted as defined by
height-for-age, based on the WHO 2006 growth standards. The proportion of
girls defined as stunted was equal to that of boys. Levels of underweight, wasting
and obesity were 9%, 6% and 2% respectively.
The risk of low versus combined high and average performance in Mathematics
at grade 7 was about three times more likely in study participants whose heightfor-
age was below -3SD and seven times more likely for those below -4SD.
Participants whose weight-for-age as defined by the WHO reference was below -
2SD were more than three times more likely to achieve a low score versus a
combined high and average score in English or first language. There was no
evidence of correlation between low birth weight, wasting and obesity and poor
education performance for both Mathematics and English results
Conclusion: We conclude that there is an association between height at age 2
years and school performance at the end of primary school.
Description
MSc (Med), Epidemiology and Biostatistics, Faculty of Health Sciences, University of the Witwatersrand
Keywords
school performance, height at age 2, adolescents