Increase in children with developmental delay: Survey on 18-month-old children in Togane city, Japan.

BACKGROUND: Individuals who visit hospitals with neurodevelopmental disorders have recently increased. To locate the cause for this increase, various factors, such as environmental and genetic ones, are being investigated. The objective of this study is to analyze the developmental delay in children and their background.

METHODS: The participants were children who underwent the checkup for 18-month-old children in Togane city, Japan, from 2011 to 2021; 4,145 children-2,147 boys and 1,998 girls with a mean age of 18.8 months-were included. To examine the tendency over time and the background, we used the questionnaire about development and lifestyle reported by parents.

RESULTS: The number of children who did not produce pointing gestures or respond to their names and low-volume sounds tended to increase over the survey period (p = 0.0125, p = 0.0435, p = 0.0275). Next, we examined the relationship between pointing gestures and lifestyle and found that there was a relationship between attending a nursery school and bedtime and pointing gestures.

CONCLUSION: A slow developmental trend over the last decade has been observed among children. The background was related to attending a nursery school and bedtime, suggesting that interaction with others and sleep are important for the development of children.