Diagnostic accuracy of Ages and Stages Questionnaire, Third Edition to identify abnormal or delayed gross motor development in high-risk infants.

ASQ-3 has poor sensitivity to identify abnormal or delayed motor development at 4 months. Using the 'Monitor' cut-off improves the diagnostic accuracy of ASQ-3 for identification of older infants with abnormal motor development who are at high risk of motor disability. However, ASQ-3 has poor sensitivity to identify motor delay. Clinical motor assessment of high-risk infants is recommended, particularly in early infancy.