Gender differences of children's developmental trajectory from 6 to 60 months in the Taiwan Birth Cohort Pilot Study

The parental report instrument is the most efficient developmental detection method and has shown high validity with professional assessment instruments. The reliability and validity of the Taiwan Birth Cohort Study (TBCS) 6-, 18- and 36-month scales have already been established. In this study, the reliability and validity of the 60-month scale was tested. The gender differences in children's longitudinal gross motor, fine motor, language and social development were also investigated. Using the dataset from the Taiwan Birth Cohort Pilot Study (TBCS-p), 2048 infants were followed up when they were 6-, 18-, 36- and 60-month-old. At the final stage, 1620 children were followed up. Development of the children was measured using the TBCS 6-, 18-, 36-, and 60-month developmental scales. The reconstructed TBCS 60-month scale yielded 16 items measuring children's development in the four dimensions of gross motor, fine motor, language and social. The scale yielded an internal consistency of 0.39-0.71. Structural equation modeling also showed good construct and predictive validity, in that the 6-, 18-, and 36-month scales were predictive of the 60-month scale. No gender differences between the gross motor dimension was found. Gender had an effect on the fine motor dimension at 36 and 60 months, language dimension at 36 months, and social dimension at 18, 36 and 60 months. Gender had a transient effect in language development and social development a continuous effect from 18 to 60 months. Thus different gender norms may need to be established to prevent misdiagnosis. The TBCS scale is a valid and reliable developmental screening instrument that can be used in continuous surveillance of children's development in community and clinical settings from 6 months to 5 years of age.