What the Evidence Does (and Does Not) Show for the Centers for Disease Control and Prevention Child Development Milestones: An Illustrative Example Using Expressive Vocabulary.

Purpose: Child development milestones are a critical tool for pediatricians and caregivers to use for developmental surveillance. Following review and selection by a panel of subject matter experts, the Centers for Disease Control and Prevention (CDC) published a revised list of milestones across multiple domains of development. Using expressive vocabulary, a key indicator of language development, as an illustrative example, the purpose of this brief review is to evaluate the evidence used to establish the CDC developmental milestones and determine whether the samples used to establish these milestones are representative of U.S. children.

Method: Authors reviewed the methods and evidence cited to determine the CDC milestones. First, authors identified each language/communication milestone that measured expressive vocabulary as number of words, followed by review of the sources cited in support of each extracted milestone. Then, data related to both milestones and sample characteristics were extracted and compiled as well as compared with data from a validated parent report measure of expressive vocabulary, the MacArthur-Bates Communication Development Inventories.

Results: Results indicated that evidence was conflicting, misaligned, or missing for the selected CDC expressive vocabulary milestones. This review also indicated that the samples used to determine the selected CDC expressive vocabulary milestones are not representative of U.S. children.

Conclusion: The striking paucity of evidence supporting the new CDC milestones for expressive vocabulary illustrates the critical need for future research in this area to establish more accurate milestones for U.S. children, with a focus on culturally inclusive large-scale data.