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Developmental delay describes the behavior of young children whose development in key mental and physical areas is slower than other children of the same age. The delay can be in any of a number of areas of development, such as movement (motor control), speaking, thinking, playing, or self-care skills.

Approximately 14% of all toddlers and preschoolers in the United States are classified as having developmental delay. However, as many as 1 in 4 children through the age of 5 are at risk for a developmental delay or disability. Early identification allows communities to provide more effective and affordable treatment during the preschool years, and can lessen the need for expensive special-education services in later childhood.

The prevalence of developmental delays in American children in the years 1997 to 2008 was 13.87%. The delays assessed included:

  • Learning disabilities (7.66% prevalence in the American population).
  • Attention deficit hyperactivity disorder (ADHD) (6.69%).
  • Autism (0.47%).
  • "Other" developmental delay (3.65%).

Physical therapists are movement experts. They improve quality of life through hands-on care, patient education, and prescribed movement. You can contact a physical therapist directly for an evaluation. To find a physical therapist in your area, visit Find a PT.

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What Is Developmental Delay?

A developmental delay is diagnosed when a child is assessed as being more than "a little behind" in performing everyday skills. The term defines a substantial lag in performance, and may be used to describe any type of delay in 1 or more of the following 5 skill areas:

  • Fine and gross motor (movement).
  • Cognitive (thinking).
  • Social and emotional.
  • Speech and language.
  • Activities of daily living.

These delays may or may not result from a specific medical condition. For example, a child with Down syndrome is identified at or before birth as having the syndrome, but also can have developmental delay. This fact holds true for any child with a disability, such as autism or cerebral palsy. Children without a specific medical condition, however, may still have a developmental delay. Early assessment is key. Parents should express any concerns, even the slightest ones, to their pediatrician or physical therapist.

The United States provides early intervention services for children with developmental delay, although each individual state has its own definition of "developmental delay." As a result, offered services may vary from state to state. Parents can consult with their pediatrician or family physical therapist to determine what services are offered in their state.

Signs and Symptoms

Parents are often the first to notice a child isn't hitting their milestones in 1 of the 5 areas of development mentioned above. However, lagging behind on a milestone attainment does not necessarily mean a child has developmental delay. Children need to demonstrate a significant delay in 1 or more areas of development.

For example, in infancy a child is first suspected to have developmental delay if common motor milestones are not being met, such as:

  • Holding the head up by 4 months.
  • Sitting by about 6 months.
  • Walking by about 12 months.

Children might be suspected of having a motor developmental delay if they are not exploring movement in a variety of ways. Sometimes children who have a motor developmental delay may also have an additional diagnosis, such as hypotonia (low muscle tone) that contributes to their difficulty with movement.

Motor development in children can often be the first area of delay that is noticed by caregivers. However, in infants and young children, all areas of development are closely connected; a delay in one area can impact progress in another. For example, learning about objects or babbling and talking can be affected if a child does not learn to sit or change positions. Sensory problems, such as hypersensitivity to touch or an inability to plan and problem-solve how to move, may also add to movement difficulties.

Children who have some or all of these problems that inhibit their movement development also may develop a fear of trying new motor skills, which can then lead to social or emotional problems.

How Is It Diagnosed?

Parents should first talk to their pediatrician about any concerns they have regarding their child's development. A physician can identify medical problems that may be having an impact on overall development, such as chronic ear infections that reduce hearing and affect the child’s speech development or balance.

Developmental delay is diagnosed by using tests designed to score a child's movement, communication, play, and other behaviors compared with those of other children of the same age. These tests are standardized—scored on hundreds of children—in order to determine a normal range of scores for each age. If children score far below the average score for their age, they are at risk for developmental delay.

A pediatrician usually will perform a screening test during infancy to determine if a child is progressing at an age-appropriate rate, often at the request of a parent who suspects the child is not performing the same skills as other children of the same age. A screening test helps to identify which children would benefit from a more in-depth evaluation. A physical therapist, who has knowledge of movement development, coordination, and medical conditions, will perform an in-depth examination to determine if a child’s motor skills are delayed and, if so, by how much they are delayed.

How Can a Physical Therapist Help?

Your physical therapist will first evaluate your child, conducting an appropriate and detailed test to determine the child's specific strengths and weaknesses. Your physical therapist will discuss your observations and concerns with you. If the child is diagnosed as having developmental delay, your physical therapist will problem-solve with you about your family's routines and environment to find ways to enhance and build your child's developmental skills.

In addition to evaluating your child and the environment in which the child moves, the physical therapist can give detailed guidance on building motor skills 1 step at a time to reach established goals. The therapist may guide the child’s movements or provide cues to help the child learn a new way to move. For example, if a child is having a hard time learning to pull herself up to a standing position, the physical therapist might show her how to lean forward and push off her feet. If a child cannot balance while standing, the physical therapist may experiment with various means of support, so he can safely learn new ways to stand.

The physical therapist will also teach the family what they can do to help the child practice skills during everyday activities. The most important influence on the child is the family, because they can provide the opportunities needed to achieve each new skill.

Your physical therapist will explain how much practice is needed to help achieve a particular milestone. A child learning how to walk, for example, covers a lot of ground during the day; your physical therapist can provide specific advice on the amount and type of activities appropriate for your child at each stage of development.

Can This Injury or Condition Be Prevented?

Prevention of developmental delay can be challenging when it is not associated with a specific medical condition; its causes may remain unclear. However, once developmental delay has been diagnosed, there are steps to take to prevent further delay or to help the child "catch up." Because this diagnosis has so much variability, the outcomes of intervention vary as well. The important thing to remember is that the earlier you intervene, the more likely it will be that your child can improve and not continue to fall behind.

It is also important to remember that babies who have little or no active "tummy time" play may be prone to developmental delay.

CAUTION: The American Academy of Pediatrics has recommended that all infants sleep on their backs to reduce the incidence of sudden infant death syndrome, or SIDS. As a precaution, many parents have avoided placing infants on their tummies altogether. However, research has shown that avoiding tummy time can slow the rate of accomplishment of motor-skill (movement) milestones. Evidence also indicates that infants who are kept in baby equipment (eg, infant chairs, carriers, sling seats at activity centers) for long periods of time are at a higher risk of motor delays than infants who have sufficient opportunities for active movement.

AAP's new recommendation, "Back to Sleep, Tummy to Play," encourages parents to let a child be on the floor to play in many different positions. This allows the child to learn how to move, and stimulates the brain and muscles so that rolling, reaching, crawling, and eventually walking can be achieved. Experiencing lots of different positions allows children to experiment with their bodies and build new movements. And exploring new movements helps them learn to think differently, and may even stimulate speech and social skills.

What Kind of Physical Therapist Do I Need?

All physical therapists are prepared through education and experience to treat a wide variety of conditions and injuries. For children with developmental delay, you may want to consider:

  • A physical therapist who is experienced in treating children with developmental delay.
  • A physical therapist who also is a board-certified clinical specialist or has completed a residency or fellowship in pediatric physical therapy. This physical therapist has advanced knowledge, experience, and skills that may apply to this condition.

You can find physical therapists who have these and other credentials by using Find a PT, the online tool built by the American Physical Therapy Association to help you search for physical therapists with specific clinical expertise in your geographic area.

General tips when you're looking for a physical therapist (or any other health care provider):

  • Get recommendations from family, friends, or other health care providers.
  • Ask about the physical therapists' experience in helping children with developmental delay and their families.
  • Be prepared to describe your concerns in as much detail as possible.

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The American Physical Therapy Association (APTA) believes that consumers should have access to information that could help them make health care decisions, and also prepare them for their visit with their health care provider.

The following articles provide some of the best scientific evidence related to physical therapy treatment of developmental delay. The articles report recent research and give an overview of the standards of practice for treatment of developmental delay both in the United States and internationally. The article titles are linked either to a PubMed* abstract of the article or to free full text, so that you can read it or print out a copy to bring with you to your health care provider.

Adolph KE, Berger SE. Physical and motor development. In: Bornstein MH, Lamb ME, eds. Developmental Science: An Advanced Textbook. 6th ed. East Sussex, United Kingdom: Psychology Press; 2011:241–302.

Rosenberg SA, Zhang D, Robinson CC. Prevalence of developmental delays and participation in early intervention services for young children. Pediatrics. 2008;121:e1503–e1509. Article Summary in PubMed.

Center for Parent Information and Resources. National dissemination center for children with disabilities. Accessed February 13, 2018.

National Early Childhood Technical Assistance Center. State definitions of developmental delay.  Published July 2006. Accessed February 13, 2018

American Academy of Pediatrics. Back to sleep campaign. Accessed February 13, 2018

Pathways. Accessed February 13, 2018 Accessed February 3, 2021.

Centers for Disease Control and Prevention. Increase in Developmental Disabilities Among Children in the United States. Updated May 16, 2022. Accessed May 23, 2022.

*PubMed is a free online resource developed by the National Center for Biotechnology Information (NCBI). PubMed contains millions of citations to biomedical literature, including citations in the National Library of Medicine’s MEDLINE database.

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