Linear Growth and Child Development in Low- and Middle-Income Countries: A Meta-Analysis

Abstract

BACKGROUND AND OBJECTIVE: The initial years of life are critical for physical growth and broader cognitive, motor, and socioemotional development, but the magnitude of the link between these processes remains unclear. Our objective was to produce quantitative estimates of the cross-sectional and prospective association of height-for-age z score (HAZ) with child development. METHODS: Observational studies conducted in low- and middle-income countries (LMICs) presenting data on the relationship of linear growth with any measure of child development among children <12 years of age were identified from a systematic search of PubMed, Embase, and PsycINFO. Two reviewers then extracted these data by using a standardized form. RESULTS: A total of 68 published studies conducted in 29 LMICs were included in the final database. The pooled adjusted standardized mean difference in cross-sectional cognitive ability per unit increase in HAZ for children ≤2 years old was +0.24 (95% confidence interval [CI], 0.14–0.33; I2 = 53%) and +0.09 for children >2 years old (95% CI, 0.05–0.12; I2 = 78%). Prospectively, each unit increase in HAZ for children ≤2 years old was associated with a +0.22-SD increase in cognition at 5 to 11 years after multivariate adjustment (95% CI, 0.17–0.27; I2 = 0%). HAZ was also significantly associated with earlier walking age and better motor scores (P < .05). CONCLUSIONS: Observational evidence suggests a robust positive association between linear growth during the first 2 years of life with cognitive and motor development. Effective interventions that reduce linear growth restriction may improve developmental outcomes; however, integration with environmental, educational, and stimulation interventions may produce larger positive effects.