Objective  To study the cognitive development of infants by using the Bayley Scales of Infant Development (BSID-Ⅲ) Scale.

  Methods  A total of 742 infants and young children who were routinely examined at the child care clinic of Changzhou Maternal and Child Health Hospital were selected and a randomized cross-sectional study was performed for them. Cognitive ability was used as the dependent variable and other influencing factors were used as independent variables to establish a regression equation. The cognitive development status and influencing factors of infants were analyzed by BSID-Ⅲ.

  Results  Age, birth weight, premature delivery, language understanding, language expression, fine motor and big motor development of infants had significant effects on cognitive ability (P < 0.05). There was no significant difference between the two groups in the number of delivery, and parents′ educational background (P>0.05).

  Conclusion  The development of infants aged 0 to 18 months using BSID-Ⅲ in Changzhou City is generally in good conditions. Low birth weight and preterm birth affect cognitive development within 18 months, and language understanding, language expression, fine motor and large motor development promote cognitive development.