Why was crawling eliminated from CDC developmental milestones?

by Juliana Plank, Doctor of Physical Therapy

I was surprised to hear that the CDC updated developmental milestones for the first time in 20 years and I was shocked that crawling was omitted as a milestone altogether.

According to the CDC, the guidelines were revised to prompt parents and pediatricians to screen for and refer infants to early intervention as soon as the delay is identified. The criteria for the new guidelines were established in 2017, pre Covid-19, and according to the CDC, do not take the impact of mask measures and stay at home guidelines into account. The new milestones are based on the idea that 75% of children achieve that milestone by a particular age. Previous milestones were established based on 50% of children achieving the milestone by the particular age. Previous guidelines often led parents to learn that their child was technically “delayed” relative to age matched peers, but were often encouraged to “give it time” to see if their baby could catch up.

According to the CDC, the new guidelines are meant to be more straightforward. If your child has not achieved a milestone by a certain age, go straight to early intervention, don’t wait and see. A more straightforward pathway of when to start early intervention sounds like a promising idea. But why was crawling eliminated as a milestone all together? I was so curious, I had to find out more.

The new CDC guidelines eliminated a total of 216 milestones, including crawling. This accounts for 56.6% of milestones that were included in previous guidelines.

New guidelines were based on commonly used screening and evaluation tools as well as "published clinical opinion." According to The American Academy of Pediatrics article, Evidence-Informed Milestones for Developmental Surveillance Tools, published in March 2022, Crawling was eliminated because "little/no normative data regarding when the milestone/part of the milestone should be achieved by 75% of children.”(1) In other words, although crawling is included in well regarded evaluation tools there is no empirical evidence to support the idea that 75% of children crawl. But is there evidence to support that 75% of 9-month old's sit? Or that 18-month old's climb on and off of adult furniture independently? Not that I am aware of.

So that led me to, what kind of “empirical evidence” do we have about crawling? Studies show crawling impacts how a child holds a pencil at age 5, improves a child’s postural control and improves memory retrieval in new environments. Although the peer reviewed information about crawling is limited, the evidence that crawling does provide positive functional gains is out there.

In my opinion, crawling should be included in the CDC guidelines. It meets the criteria to be included in assessment tools, and the small amount of evidence we have about it is positive. I don’t see evidence about 75% of children achieving all of the other milestones that the CDC did include.

So what does this mean for parents? I urge parents to take this omission from the CDC with a grain of salt and to consider the potential benefits of crawling including building shoulder stability, abdominal and hip strength, hand eye coordination and joint stability. Ultimately, parenting is about balancing unreasonable expectations with your hopes and dreams for your child. If you are concerned your child is not crawling, reach out to your pediatrician or a physical therapist to help determine why they are not crawling and to discuss how to encourage crawling.

My hope, is that professional outrage to protect and promote this skill will lead to further studies about the benefits and effects and percentage of children who crawl. In the meantime, we continue to rely on the CDC for the best practices about development, mask wearing, social distancing and vaccinations. As parents, we can incorporate their perspectives into how we view our children and the world but we should not use these guidelines in lieu of our own best judgement. Crawling is an essential skill for development and it will have its moment to shine in the future.

Learn more about Juliana Plank at Juliana Plank Physical Therapy.

1 Evidence-Informed Milestones for Developmental Surveillance Tools

2 Franzsen, D. and Visser, M. (2010). The Association of an Omitted Crawling Milestone with Pencil Grasp and Control in Five- and Six-Year-Old Children. South African Journal of Occupational Therapy 40(2), 20.

3 Nichols, D. (2005). Development of postural control. In Jane Case-Smith (Ed.), Occupational therapy for children, 5th edition (p. 279). St. Louis, MO: Elsevier Mosby.
4 https://pubmed.ncbi.nlm.nih.gov/17286842/