Contextual and socioeconomic variation in early motor and language development

Abstract

Objective To compare early motor and language development of children <3 years of age growing up in high-income and low-income contexts. Design Cross-sectional study. Setting We analysed differences in motor and language skills across study sites in Cambodia, Chile, Ghana, Guatemala, Lebanon, Pakistan, the Philippines and the USA. Main outcome measure Cognitive and language development assessed with the Caregiver Reported Early Development Instruments (CREDI) tool. Results 4649 children aged 0-35 months (mean age=18 months) were analysed. On average, children in sites with a low Human Development Index (HDI) had 0.54 SD (95% CI -0.63 to -0.44) lower CREDI motor scores and 0.73 SD (95% CI -0.82 to -0.64) lower language scores than children growing up in high HDI sites. On average, each unit increase in national log income per capita was associated with a 0.77-month (95% CI -0.93 to 0.60) reduction in the age of motor milestone attainment and a reduction in the age of language milestone attainment of 0.55 months (95% CI -0.79 to -0.30). These observed developmental differences were not universal: no developmental differences across sites with highly heterogeneous socioeconomic contexts were found among children growing up in households with highly educated caregivers providing stimulating early environments. Conclusion Developmental gaps in settings with low HDI are substantial on average, but appear to be largely attributable to differences in family-level socioeconomic status and caregiving practices. Programmes targeting the most vulnerable subpopulations will be essential to reduce early life disparities and improve long-run outcomes.