Has the COVID-19 pandemic altered social inequalities in child development? A time trend analysis of developmental delays in preschool children by parental education

Background Child development may have deteriorated during the COVID-19 pandemic, with children from vulnerable backgrounds potentially facing the greatest risks. This study examined time trends in developmental delays among preschool children and whether inequalities in these delays by parental education changed with the onset of the pandemic. Methods Analyses used mandatory School Entry Examinations (SEE) in the Aachen region, Germany, covering ten cohorts (2015–2024) and restricted to children identified as being at risk for developmental delays ( n = 15,299). The outcome was the number of delayed domains among six assessed. A segmented (interrupted time series) Poisson regression estimated the pre-pandemic trend, the level shift at the break between the 2020 and 2021 cohorts, and the subsequent change in trend, with inequalities by parental education expressed on both the relative and absolute scale. Multiple imputation and inverse probability weighting were applied. Results Children of less-educated parents showed significantly more delays in every cohort. Delays increased significantly before the pandemic at a comparable rate in all educational groups. Delays rose abruptly in the 2021 cohort in all groups and declined thereafter, remaining elevated. Between the two periods, relative inequality narrowed significantly because delays increased proportionally more among children with moderate and high parental education, whereas absolute inequality was unchanged. Conclusion Children from families with lower educational attainment continued to experience a consistently higher burden of developmental delays. The first cohort assessed after the onset of the pandemic showed an abrupt, population-wide increase, which reduced inequality on a relative scale while leaving the absolute gap between educational groups unchanged. Public health strategies must address both persistent structural disparities and the broad vulnerabilities revealed by global crises.