Clinical linguistic and auditory milestone scale: prediction of cognition in infancy.

At each well-child examination between birth and two years, parents of 448 infants were questioned about their child's age at attainment of 25 linguistic and auditory milestones. Parental reports were compared with the results of independently administered Bayley Mental Developmental Index (MDI) at one year of age. Parental recall of information was high, ranging from 70 to 99 per cent for 21 of the 25 milestones. The milestone performance of infants with normal MDI scores showed an orderly, sequential progression of expressive and receptive language. Across the entire population studied, the correlation between milestone attainment and MDI was statistically significant for 24 of the 25 milestones, and later attainment of milestones correlated with lower MDI. As a group, 'delayed' infants (MDI less than 68) attained milestones significantly later than 'average' infants (MDI 85 to 116) for 20 of 25 items. Attention to linguistic and auditory milestones early in infancy can contribute to the early detection and diagnosis of mental retardation and disorders of communication.