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The first time a child smiles, talks, crawls, and walks are special memories for families. They’re also important developmental milestones.

As children grow, they reach milestones in actions and behavior — usually by a certain age.

When children don’t achieve certain milestones by the usual time, it’s referred to as a developmental delay. An estimated 15% of children ages 3 to 17 have a developmental delay, according to the American Academy of Family Physicians.

With recognition and support, such as therapy, many developmental delays resolve over time. In other cases, it could be a sign of a developmental disability.

What Are Developmental Milestones?

Your pediatrician should ask questions about your child’s development at each well-child visit.

Developmental milestones measure how your child is growing and developing compared to other children the same age. Milestones fit into several categories:

• Physical growth.
• Language/vocabulary development.
• Cognitive development.
• Sensory and motor skills.
• Emotional and social development.

What Are Developmental Delays?

If your child does not reach certain milestones by the expected age, it could be a sign of a developmental delay.

Developmental milestones measure the expected age for skills, but they aren’t concrete. Some children develop more slowly in certain areas than others. For example, it’s not necessarily a developmental delay if your child isn’t babbling by 4 months.

But, if your child consistently misses developmental milestones, it can be cause for concern.

The Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatricians (AAP) updated their joint guidelines for typical child developmental milestones in February 2022. They recommend pediatricians observe a child’s development at each well-child visit and conduct developmental screenings at 9, 15, 18, and 30 months and autism screenings at 18 and 24 months.

In concert with the AAP, the CDC outlines specific milestones at the following ages:

• 2 months
• 4 months
• 6 months
• 9 months
• 1 year
• 15 months
• 18 months
• 2 years
• 30 months
• 3 years
• 4 years
• 5 years

The earlier a child is identified with a developmental delay the better so that treatment and learning interventions can begin. If you have concerns about your child’s development, talk with your pediatrician and request a developmental screening.

Developmental Delay Risk Factors

Different factors, both genetic and environmental, can lead to developmental delays. Some risk factors include:

• Genetic disorders.
• Pregnancy/birth complications.
• Use of drugs or toxins (smoking, drinking alcohol) during pregnancy.
• Trauma.
• Infections.
• Stroke.
• Malnutrition.

Often there is no identifiable cause or reason for a developmental delay or missed milestone.

Developmental Delay Treatment

Developmental delays are treatable when diagnosed early. If your child has a developmental delay, several therapies can help him or her to catch up:

• Occupational therapy.
• Physical therapy.
• Speech therapy.
• Cognitive/behavioral therapy.

Every U.S. state offers early intervention services for children with developmental delays. The Pennsylvania early intervention program covers children from birth through age 5, at no cost to families.

What Are Developmental Disabilities?

If problems persist, it could be a sign of a developmental disability. A developmental disability is a long-term (often lifelong) problem that can cause physical, intellectual, or emotional challenges.

According to the National Association of Councils on Developmental Disabilities, more than 5 million Americans have developmental disabilities. Intellectual disabilities are most common.

Developmental delays can be associated with diagnoses such as:

• Attention-deficit/hyperactivity disorder.
• Autism spectrum disorder.
• Cerebral palsy.
• Down syndrome.
• Fetal alcohol syndrome.
• Fragile X syndrome.
• Muscular dystrophy.
• Tourette syndrome.

They also can be the result of conditions such as:

• Blindness/vision loss.
• Deafness/hearing loss.
• Intellectual disabilities.
• Language and speech disorders.
• Learning disabilities.

If you’re concerned about your child’s development, talk to your pediatrician at the next well-child visit. For more information, visit UPMC Children’s Hospital of Pittsburgh online or call us at 412-692-5325.

Editor's Note: This article was originally published on August 4, 2021, and was last reviewed on November 17, 2022.