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Developmental Delay

  • When a child’s progression through predictable developmental phases slows, stops, or reverses
  • Symptoms include slower-than-normal development of motor, cognitive, social, and emotional skills
  • Treatment includes occupational therapy, speech therapy and/or physical therapy services
  • Involves Child Study Center; Pediatrics

Developmental Delay


Most children move fairly smoothly through the predictable phases of child development—but some experience difficulties. A baby may have a birth defect that interferes with his development, causing him to progress in fits and starts, meeting some milestones on time and others much later. Some children develop normally for months or even years but then falter, with development slowing down, stopping, and sometimes even going backward. 

These are all examples of what’s called “developmental delay.” Whatever the specifics of an individual case, Yale Medicine’s Child Study Center provides a comprehensive assessment that can clarify the problem and identify what support a child needs to help him fulfill his potential.

What causes developmental delay?

Prematurity, medical problems (ranging from stroke to chronic ear infection), lead poisoning, and trauma all have the potential to cause developmental delay, but sometimes the cause is unknown. Ann L. Close, PhD, a Yale Medicine Child Study Center clinical psychologist and associate director of the Infancy & Early Childhood Program, specializes in the assessment and treatment of children under 5. She urges all parents concerned about a child’s development to discuss it with their pediatrician. 

“Parents know their children best and are usually the first to notice or be worried about the rate of a child’s development,” she says. A pediatrician can perform some basic, in-office screening tests that can help to determine whether it’s okay to give the child a bit more time to catch up or if it might be wise to schedule an assessment.

What does it mean if a child has developmental delay?

Child development experts have identified ranges within which infants, toddlers, and children typically master certain motor, cognitive, social,and emotional skills, says Close. Whether a child meets a specific milestone (such as learning to crawl or speak in sentences) early or late isn’t important so long as it’s within the range of normal; most children do some things early and others later. 

But if a child’s overall development occurs slower than normal, is consistently slow in one area (such as motor skills or using language), or seems to stop moving forward, he may have a developmental delay. “Children are motivated to learn about their world,” Close says. “We become worried when we don’t see the motivation to move forward,” noting that this can occur because of emotional upset, trauma, or as a reaction to an environment that isn’t meeting the child’s developmental needs.

How are developmental delays diagnosed?

Our Infancy & Child Development Program offers developmental evaluations for infants, toddlers, and children up to age 5. A pediatrician referral is welcome but not required.

Parents are asked to provide information about the child’s developmental history, including the pregnancy and birth, and medical history. One-on-one diagnostic play sessions and evidence-based measurement tools are used to gather data about the child’s mastery of language, motor skills and cognitive, social and emotional development. That information, combined with insights gathered from close observations of the child, leads to a final report, which is shared with the parents at a feedback session. 

“We spend a lot of time trying to get to know the same child the parent sees at home. We talk to the child and parent together, we try to meet the siblings, and we collect information from other places a child goes, such as school and daycare," says Christiana Mills, MSW, LCSW, program coordinator of the Child Study Center’s Outpatient Clinical Services. "We work hard to understand what the parent is seeing and we think through how what they see and what we see come together.”

The evaluation concludes with a feedback session, during which the findings and recommendations are shared with the parents.

How are developmental delays treated?

If a child is found to have developmental delays, the next step is identifying the services that can provide the support and assistance the child and family needs. These may include home visits from the state-sponsored Birth to Three program, outpatient occupational, speech or physical therapy, school-based special education services, and/or some form of psychotherapy for the parent and child.

What is unique about Yale Medicine Child Study Center's approach to diagnosing and treating developmental delay in children?

Arnold Gesell, MD, PhD, the first director of the Child Study Center, founded in 1911, is widely recognized as one of the first to focus comprehensive resources on the study of normal child development. Dr. Gessell used frame-by-frame film analysis to document developmental milestones, step by step, creating the monumental “Atlas of Infant Behavior,” containing 3,200 photographs. 

Since then the Child Study Center has become internationally known for supporting children in the full context of their lives. With the goal of helping every child achieve her fullest potential, we offer a welcoming environment highly focused on helping parents feel safe, understood, and supported, while also identifying and providing the treatments and supports a child needs to thrive, Close says.