Developmental milestones are a helpful tool for both parents and pediatricians to get a general sense of how a child is developing. And while they’re not a perfect metric—not all babies will meet all milestones at exactly the same time, by any means—they can be useful in spotting signs where a child may need more support.

The original milestone guidelines you’ve likely seen at your child’s well visits were created in 2004 under the Centers for Disease Control and Prevention (CDC)’s Learn the Signs. Act Early (LTSAE) program, and haven’t been updated since.

That was 18 years ago—and so much has changed since then, especially our understanding of social-emotional development. 

With a goal of making early identification of developmental delays easier, experts from The American Academy of Pediatrics (AAP) and Centers for Disease Control and Prevention (CDC) recently convened to update the checklist of developmental milestones for infants and toddlers. 

“This has been a need that is long overdue,” Paul Lipkin, a pediatrician and director of medical outpatient services at the Kennedy Krieger Institute in Baltimore, tells The Washington Post. Dr. Lipkin was on the committee that updated the milestones. 

Changing the percentile to better reflect the majority

The newly revised developmental milestones are written in family-friendly language and identify the behaviors that 75% or more of children can be expected to exhibit at a certain age. Previous LTSAE checklists used 50th percentile milestones or listed an average age of achievement.

The main issue with using the average age of achievement approach is that only half of children were expected to achieve that milestone by that age, the AAP writes in a press statement. This often led to a wait-and-see approach, rather than early action to mitigate future delays. 

Now, the new guidelines specify that 75% of children are able to reach these behavior and achievement milestones by a certain age, offering doctors and parents a clearer picture of typical developmental behavior, like picking up cereal with their fingers (1 year) or banging two objects together (9 months). 

You can view the milestones checklists by age here.

“Clinicians reported that following the former guideline often was not helpful to individual families who had concerns about their child’s development; in some cases, it led to delays in diagnoses as clinicians and families chose a wait-and-see approach,” states the AAP.

“The earlier a child is identified with a developmental delay the better, as treatment as well as learning interventions can begin,” says Dr. Lipkin in the statement. “At the same time, we don’t want to cause unnecessary confusion for families or professionals. Revising the guidelines with expertise and data from clinicians in the field accomplishes these goals. Review of a child’s development with these milestones also opens up a continuous dialogue between a parent and the health care provider about their child’s present and future development.”

A new focus on developmental surveillance

The newly revised guidelines also place an emphasis on developmental surveillance rather than screening tests, encouraging an open dialogue between parents and their child’s pediatrician throughout the first year and beyond to continue monitoring behavior to meet developmental goals.

The updates also include social-emotional markers that may suggest an autism diagnosis if not met by a certain age, such as smiling to get attention, which should happen in 75% of 4-month-olds. More social-emotional milestones were added for other ages, too, such as showing caregivers affection by hugging and kissing at 15 months. 

Having key indicators for potential signs of autism can better equip parents to advocate for early intervention, which, studies show, can help reduce the chance of an autism diagnosis in later years. One 2021 study found that parent-led therapy in babies showing early signs of autism spectrum disorder (ASD) reduces the chance of later ASD diagnosis at age 3 by 66%. 

According to the CDC, additional changes to the LTSAE milestones include:

  • Adding checklists for ages 15 and 30 months; now there is a checklist for every well-child visit from ages 2 months to 5 years
  • Identifying additional social and emotional milestones (Example: Smiles on their own to get your attention, age 4 months)
  • Removing vague language like “may” or “begins” when referring to certain milestones and using plain language instead
  • Removing duplicate milestones
  • Providing new, open-ended questions to use in discussion with families (Example: Is there anything that your child does or does not do that concerns you?)
  • Revising and expanding tips and activities for developmental promotion and early relational health

Your pediatrician’s office should have an updated copy of the new milestones ready for your next well visit, but you can also print the pdfs for home use. The CDC also offers a free Milestone Tracker app