Bayley III is a valid and reliable comprehensive assessment tool for children between the corrected ages of 15 days and 42 months. Bayley III evaluates cognitive, receptive language, expressive language, fine motor, and gross motor development. As Bayley III shows children's holistic development, we preferred to use it as a primary outcome measure. Bayley III includes raw scores, scale, composite, percentile, and growth scores. High points indicate better development. There are no developmental norms of Bayley III for the population of Türkiye. Therefore, we used the American term—children development norms. We reported Bayley III by using the scale score ranging from 1 to 19 points to give all subfields. We also used the composite score to identify children with and without developmental delays. We accepted the 85 composite scores to identify developmental delays, as it is recommended to use the cut‐off point for preterm infants (Albers et al., 