Insights from normalized developmental rates across diverse domains in early childhood: a National Longitudinal...

Understanding child development requires a nuanced exploration of developmental rates over time rather than relying on single-time-point assessments. However, comparing developmental rates in preschool children across domains is limited by the use of distinct assessment tools for various age groups.

This study aims to analyze the impact of age on child developmental rates across diverse domains among young children.

The study involved 6745 young children from two cohorts of the Kids in Taiwan: National Longitudinal Study of Child Development and Care (KIT): M3 (aged 3 months) and M36 (aged 36 months) groups. Cognitive, language, and motor domains were assessed through in-person interviews, with follow-ups conducted for the M3 group at 12 to 36 months and the M36 group at 48 to 72 months. Overcoming challenges in diverse developmental domains and ages, the study used varied questionnaire versions with common items and Rasch analysis, emphasizing breakthroughs in addressing developmental disparities through normalized child developmental rates over time.

Normalized child developmental rates substantially declined with age for the M3 group, contrasting with minimal changes for the M36 group. Significantly higher rates were observed between 3 and 24 months (2.08-5.66 times) compared to 24-36 months. Motor development consistently showed greater rates than cognitive and language development, especially before 12 months.

This study shows that age plays critical role in shaping normalized child developmental rates across various domains, emphasizing the sensitive birth-to-two-year window for rapid developmental changes. These findings can provide the importance of early intervention for policymakers.