Long-term association between the COVID-19 pandemic and language development in children aged 18 months: effect modification by sex, childcare location and family size.

Publication date: Dec 23, 2025

We evaluated the long-term association between the COVID-19 pandemic and the language development of children aged 18 months by comparing prepandemic and pandemic periods in Japan. This repeated cross-sectional study included 39 840 children attending 18-month health check-ups conducted by the Okayama City Public Health Center (January 2017-March 2024). We compared language development indicators before (January 2017-March 2020) and during (April 2020-March 2024) the pandemic, with the latter divided into early (April 2020-March 2022) and late (April 2022-March 2024) periods. The primary outcome was the proportion of children requiring language development follow-up (children who did not meet any one of the three questions on language development). The secondary outcome was the proportion of children who could not say ≥3 meaningful words (one of the three questions). Risk ratios (RRs) and 95% CIs were estimated adjusting for confounders, with subgroup analyses by sex, childcare location (home, nursery school) and family size (≤3, ≥4). Compared with the prepandemic period, increased RRs were observed during the pandemic: 1. 19 (95% CI 1. 15 to 1. 22) for the primary outcome and 1. 16 (95% CI 1. 11 to 1. 22) for the secondary outcome. RRs were higher in the late than in the early period. Adverse associations were more pronounced in girls than boys, and in children cared for at home. The long-term association between the pandemic and language development at 18 months suggests the need for more comprehensive support for high-risk families.

Semantics

Original Article