Linear growth beyond 24 months and child neurodevelopment in low- and middle-income countries: a systematic review and meta-analysis

To synthesize available evidence on the association between change in linear growth (height for age z score, HAZ) beyond the first two years of life with later child neurodevelopment outcomes in Low- and middle-income countries (LMICs). We searched PubMed, Web of Science, and EMBASE for cohort studies on the association between change in HAZ after age two and neurodevelopment outcomes in middle or late childhood. Data extraction was done independently by two reviewers. A total of 21 studies, that included 64,562 children from 13 LMICs were identified. Each unit increase in change in HAZ above two years is associated with a + 0.01 increase (N = 8 studies, 27,393 children) in the cognitive scores at 3.5 to 12 years of age and a + 0.05-standard deviation (SD) increase (95% CI 0.02 to 0.08, N = 3 studies, 17,830 children) in the language score at 5 to 15 years of age. No significant association of change in HAZ with motor (standardized mean difference (SMD) 0.04; 95% CI: -0.10, 0.18, N = 1 study, 966 children) or socio-emotional scores (SMD 0.00; 95% CI: -0.02, 0.01, N = 4 studies, 14,616 participants) was observed. Changes in HAZ after the first two years of life appear to have a small or no association with child neurodevelopment outcomes in LMICs.