Measuring catch-up growth in malnourished populations

Abstract

Background and aim: Numerous recent studies measure catch-up growth by regressing adult or pre-adolescent height on early childhood height. Using simple statistical theory and data from a healthy and well-nourished population, this paper shows that these tests are uninformative about the extent of catch-up growth. The study also provides new empirical evidence on pubertal catch-up growth using longitudinal data for rural Tanzania.

Subjects and methods: The 1970 British Cohort Study is used to demonstrate the flaws in the recent literature using regression techniques to study catch-up growth. The data for the empirical analysis come from the Kagera Health and Development survey—a longitudinal study spanning two decades. The final sample includes 540 children whose heights are measured in early childhood and in adulthood. Catch-up growth is measured as the change in height-for-age z-score over time.

Results: The mean HAZ-score in the cohort improves from −1.86 in early childhood to −1.20 in adulthood. Without catch-up growth, children would have been 4.5–5 centimetres shorter adults. Graphical analysis shows that most of this catch-up growth takes place in puberty.

Conclusion: Catch-up growth after early childhood is possible. Puberty seems to offer an opportunity window for recovery.

• African height puzzle
• compensatory growth
• children
• height
• under-nutrition

Acknowledgements

I am grateful to Alexander Moradi and Andy McKay for their invaluable support during this project. I also thank Barry Reilly and the seminar participants at Sussex University for useful comments. I gratefully acknowledge the financial support from the Economic and Social Research Council [grant number ES/I900934/1], the Finnish Cultural Foundation and Yrjö Jahnsson Foundation. The fieldwork for the Kagera Health and Development Survey was primarily funded by the Rockwool Foundation and the World Bank, and was conducted by EDI-Tanzania. I thank the Centre for Longitudinal Studies, Institute of Education for the use of 1970 British Cohort Study and the UK Data Archive and Economic and Social Data Service for making the data available.