Objectives Language development is assessed in health checkups for children aged 18 and 36 months in public health centers to identify those with language delay and promote language development in early childhood. This study examines factors associated with language development to provide parents with evidence-based information.Methods We used the data from the health checkup questionnaire filled by parents of 18- and 36-month-old children born between April 2019 and March 2020 and undergone 18- and 36-month health checkups by March 2023 in Yokohama city, Japan. The sample included 12,710 children. Language delay was defined as the inability to speak at least three words and three-word sentence for 18- and 36-month-old children, respectively. Bivariate and multivariate logistic regression were applied to assess the odds ratios (OR) for language delay in 18 and 36 months and associated factors; birth order, weeks of birth, mother's age, and existence of a ternary relationship in 18 months. Moreover, we assessed the OR for language delay in 18 and 36 months to understand the language development in early childhood.Results Language delay was observed in 17.5% and 6.7% of 18- and 36-month-old children, respectively. Multivariate logistic regression analysis revealed significant associations of language delay in 18-month-old children and assessed factors; first-born children (OR; 1.39 [1.25-1.53]); preterm birth (OR; 1.80 [1.46-2.21]); and pregnancy at age ≥ 35 years (OR; 1.24 [1.12-1.37]), but no significant associations of language delay in 36-month-old children and these factors. Language delay in 18- and 36-month-old children were significantly associated, adjusting for potential confounders (OR; 6.81 [5.79-8.00]).Conclusion Children's background since birth should be checked to assess 18-month language development during health checkups. Children with language development delay at 18-month health checkups should be identified and followed for further support.
Keywords: health checkups for infants; language delay; maternal and child health.