Stability of the Bayley mental scale of infant development with high risk infants

This study examines stability of scores on the Bayley Mental Scale of Infant Development Second Edition (BSID-II) across the first two years of life for high risk infants. BSID-II scores in the first and second year of life for 16 infants with Down syndrome and 17 medically fragile infants were compared to Bayley Mental Scale of Infant Development (BSID) scores for 33 matched infants. A three-way interaction of Group, Time, and Bayley Version on developmental quotient (DQ) scores revealed that, for infants with Down syndrome, scores decreased from the first to second year for both test versions, but for medically fragile infants, BSID scores decreased from the first to second year and BSID-II scores increased from the first to second year. These results indicate that the BSID-II is sensitive to patterns of developmental changes in the first two years of life that are specific to infants with Down syndrome and to medically fragile infants. Together with other findings regarding mental development in specific groups of high risk infants, they invite cautious interpretation of assessments conducted in the first two years of life. Specifically, results from BSID-II assessments of high risk infants in the first year of life should not be used for predictive purposes, and must be interpreted differently for infants with Down syndrome than for infants with multiple medical conditions.