Should you use crawling as a developmental milestone when assessing your paediatric patients?

Crawling is a key component of development milestone checklists the world over, but new research suggests that crawling is highly variable and not essential for development.

The Centers for Disease Control and Prevention (CDC) in the United States estimates that about 1 in 6 children has a developmental disability, but less than half of these are identified before school age. This is important because children with developmental problems are at increased risk for poor outcomes in many areas important to health, well-being, and success in life, and early intervention can improve a child’s skills and abilities.

Developmental milestone checklists have become commonplace essential tools to help caregivers and health professionals alike to identify children who are not developing in line with expected norms.

Best Practice in Developmental Skills Training

One such tool is the CDC’s paediatric surveillance program for children aged 2 months to 5 years. Learn the Signs. Act Early centres around a checklist of cognitive, social/emotional, language/communication and movement/physical development milestones.

This tool was recently updated in 2020 in response to a lack of clear sources of evidence and objective criteria in the original 2014 document. Revisions included: 1. Updating of the milestone checklist; and, 2. Streamlining of checklist items.

The revision, however, came under intense criticism by many in the therapeutic community due to controversial recommendations in the updated milestone checklist.

A new review article published in Pediatric Physical Therapy aims to deal with some of the main concerns voiced and to provide clarity and reasoning from a physiotherapy perspective.


Learn the Signs. Act Early.” Updates and Implications for Physical Therapy is written by a team of US-based academic and clinical physiotherapists. They examine the published changes and review the cited literature, as well as considering the current evidence in early childhood motor development. In particular, they address key concerns of the updated CDC paediatric surveillance program from a Physiotherapy perspective, including:

  1. A perceived lowering of milestones due to changes in some ages in the checklist items
  2. Removal of crawling from the checklist
  3. Fear that changes would lead to decreased referrals and ultimately a decrease in funding for children identified for intervention

The authors address these items through their own expert commentary, citing current research.


The updated guidelines were produced by a group of subject matter experts (convened by the American Academy of Pediatrics), who performed an extensive literature search in order to provide concrete criterion for inclusion of each milestone. 

A total of 36 articles were selected, and included published normative data, information from screening and evaluation tools and published clinical opinion. The authors highlight the diverse geographical collection of data, improving generalisability of the findings. Links to all research  and research processes are publicly available, including the methods for the literature search in an open access article in the journal Pediatrics.

There are 11 criteria used to assess milestones on the checklist. One of these criteria is the use of the 75th percentile – the age where 75% of children in the age category are expected to demonstrate the milestone. Notably this was previously set to 50% in the original milestone checklist.

Concerns from the guidelines are addressed, including:

1. Perceived lowering of milestones: 

Most motor milestone checks have remained at the same age when compared with the original 2014 edition; a perceived lowering of standards is observed because of the consistent application of a 75% criterion and not the previous 50% . This does not reflect standards of children’s development being lowered, but a repackaging of information. 

2. Removal of crawling from the checklist: 

The exclusion of crawling within the checklist was made after considerable research. Ultimately there is a current dearth of evidence linking the absence of crawling to a marker of atypical development. It was noted that the lack of evidence-based research should be seen as an opportunity to engage in research providing answers in this aspect of development.

3. Fear of decreased referrals

Multiple changes to the surveillance program are expected to increase rather than decrease rates of referral. These changes include the removal of ambiguous language such as “may” or “begins to”.  Moving of expected achievement norms for age of attainment to 75% (from 50%) means that more serious consideration needs to be given to an infant or child not meeting checklist milestones.

The authors confirm that the lack of clear sources of evidence and objective criteria for the inclusion of skills or the association of skills with specific ages in the original 2014 guidelines was addressed in the updated version.

Quick Summary and Clinical Significance

“Learn the Signs, Act Early” is designed for caregivers and health professionals to identify children requiring further screening and possible formal assessment. While aspects of its revision can be held up for debate, actual versus perceived changes should be carefully scrutinized before comment. 

The debate as to whether crawling should be included or omitted from the checklist is not given a definite answer, with the authors admitting that by no means is this a “settled science”. Instead, they highlight the paucity of research and encourage further high quality research to fully answer the question.

It is imperative that physiotherapists, as advocates of health, movement, and development understand and utilize tools such as the CDC’s surveillance program. This can aid in not only building relationships between families and therapists, but between the physiotherapy community and health practitioners as a whole.