COVID-19 pandemic and language development in children at 18 months: a repeated cross-sectional study over a 6-year period in Japan

ObjectiveTo evaluate the impact of the COVID-19 pandemic experience on language development among children, we compared language development at 18 months of age, before and during the pandemic in Japan, where strict control measures continued over a long period.MethodsThis was a repeated cross-sectional study and we included children who attended the 18-month health check-up provided by the Okayama City Public Health Center between January 2017 and December 2022 (n=33 484). We compared indicators of language development before (from January 2017 to February 2020) and during (from March 2020 to December 2022) the pandemic. Our primary outcome was the proportion of children who required follow-up for language development by the Public Health Center. The secondary outcome was the proportion of children who could not say three or more meaningful words. We estimated risk ratios (RRs) and their 95% CIs, adjusted for potential confounders.ResultsThe prevalence of the primary outcome was 33.5% before the pandemic and 36% during the pandemic. Compared with before the pandemic, increased RRs for the primary and secondary outcomes were observed during the pandemic, with RRs (95% CIs) of 1.09 (1.06-1.13) for the primary outcome and 1.11 (1.05-1.17) for the secondary outcome. Although the statistical interactions were not significant, the RRs were higher for children cared for at home than those in nursery schools and with <= 3 family members than those with >= 4 family members.ConclusionsThe COVID-19 pandemic was associated with an increased risk of impaired language development in children at 18 months. More extensive support is needed for higher risk families, as well as follow-up of long-term language development in children affected by the COVID-19 pandemic.