Did the timeframe that a child is supposed to achieve certain milestones change?

The 2004 Developmental Surveillance Milestone Checklists monitored each skill at the 50^th percentile. This rating approach might have encouraged a “wait and see” approach. The 2022 Developmental Surveillance Milestone Checklists include opportunities for rating at the 75^th percentile. The change was made to make clear what most children at a given age are expected to do and to reduce confusion about when to move forward with developmental screening.