Background: The aim of the present study was to investigate the prediction of development among 6-, 18-, and 36-month-old infants on the Bayley Scale of Infant Development (BSID).
Methods: One hundred infants were assessed using the BSID at 6 months; of these, 70 completed the 18 and 36 month assessment at follow up.
Results: Multivariate regression and structural equation modeling were used to determine predictive validity in the mental and psychomotor developmental scales. Structural equation analysis also confirmed the conceptual scheme of the stability of development from 6 to 36 months for boys. Boys had a steadier overall developmental trajectory compared to girls.
Conclusions: The validity of BSID was consistent with previous studies. The language spurt in girls, however, from 6 to 18 months affected the stability of the BSID. Thus, the gender difference in language development should be considered in clinical assessment.