2.4 | Follow-up assessments of physical and neurobehavior development
Infants participated in a follow-up survey 2~3 years after birth. Telephone interviews with parents were performed to record information on the timing of first walking and speaking. The infant’s neurobehavioural development was also assessed through phone interviews using the Questionnaires of Infant Ages and Stages third edition (ASQ-3) encompassed five developmental domains: communication, gross motor, fine motor, problem-solving, and personal social, with a maximum of 60 scores for each domain. Physical evaluation of each twin included height and weight, which were measured based on the WHO’s standards, and were conducted by qualified physicians. The height and weight measurements were standardized by two z-scores of height-for-age and weight-for-age according to the WHO Anthro program (V.3.2.2) for children five years of age or younger.