Physical growth: Is it a good indicator of development in early childhood in low- and middle-income countries?

Background: Growth and early development (ECD) are vital outcomes for children. This study aimed to examine the association between child growth and overall development in children aged 3 to 5 years in low- and middle-income countries. Methods: A secondary analysis of nationally representative data collected in UNICEF's Multiple Indicator Cluster Surveys (MICS) and national Demographic and Health Surveys (DHS). The early development of children aged 3 to 5 years from the randomly selected households was ascertained using a 10-item scale which assessed four developmental domains: language-cognitive, physical, socio-emotional, and approaches to learning with a total development score ranging from 0 (the least optimal) to 10 (the most optimal). Children's growth, the height-for-age Z score (HAZ), was calculated using the WHO Child Growth Standards. Unadjusted (Pearson's correlation coefficient, r) and adjusted estimations (standardised mean difference (SMD) adjusted for child sex, child age, and household wealth index) of the magnitude of the association between HAZ and ECD scores were calculated for each country. Results: Data contributed by 178,393 children aged 36 to 59 months from 55 countries were included in the analyses. The pooled r between HAZ and standardised ECD scores was 0.12 and the pooled adjusted SMD was 0.06. The r ranged from ~ 0 in Barbados, Lebanon, and Moldova to 0.32 in Pakistan and 0.36 in Nigeria. Overall, 47/55 countries had correlation coefficients less than the cut-off for a small association. The adjusted SMDs were ~ 0 in 20 countries. All SMDs were lower than the cut-off for a small effect size. The magnitudes of the association were highest in South Asia and lowest in Middle East and North Africa, and lowest in the highest HDI group. Conclusions: The association between growth and development in early childhood appears to be primarily a co-occurrence because the magnitude of the association varies among settings from no association in higher-income countries to a moderate level in low-income countries. In low-income countries, interventions targeting child growth and ECD should be integrated given their common risks frequency in these settings. Overall, growth is not a sensitive and therefore suitable indicator of child development.