Down Syndrome

What is Down syndrome?

Down syndrome is a genetic condition that happens when a child is born with an extra chromosome. The extra chromosome affects the way the child’s brain and body develop, leading to developmental delays, intellectual disability and an increased risk for certain medical issues.

Down syndrome is the most common genetic cause of intellectual disability, affecting approximately 1 in every 700 children. It is named for John Langdon Down, the British physician who first recognized the traits of Down syndrome in 1866.

The chance that a baby will be born with Down syndrome increases with a mother’s age:

  • 1 baby out of every 1,000 born to women under age 30
  • 1 baby out of every 400 born to women older than 35
  • 1 baby out of every 60 born to women older than 42

Some expectant parents choose to undergo prenatal testing to find out in advance if their child will have Down syndrome. These optional tests, performed during pregnancy, can identify a fetus’s sex, age, size and placement in the uterus. They can also detect conditions such as Down syndrome, congenital heart defects, genetic conditions and other birth defects.

Down syndrome and intellectual disability

Most children with Down syndrome have some level of intellectual disability ⎯ usually in the mild to moderate range. People with mild intellectual disability are usually able to learn how to do everyday things like read, hold a job, and take public transportation on their own. People with moderate intellectual disability usually need more support.

Many children with Down syndrome can participate in regular classrooms, though they may need extra help or modifications. Thanks to widespread special education and community programs, more and more people with Down syndrome graduate from high school, attend college and work in their communities.

To help children with Down syndrome reach their highest potential, parents can seek out assistance programs as early as possible. By law, every state must provide developmental and special education services for children with Down syndrome, starting at birth with early Intervention and then continuing with public education until age 21.

Down syndrome and medical problems

Children with Down syndrome can have a variety of health issues. About half are born with a congenital heart defect, a structural problem with the heart that develops during pregnancy.

The most common congenital heart defects in children with Down syndrome include:

Many children with heart defects also develop pulmonary hypertension, a condition that can cause lasting lung damage if left untreated.

Other health issues that commonly affect children with Down syndrome include:

How we care for Down syndrome

The Boston Children’s Hospital Down Syndrome Program is one of the oldest and largest programs for children with Down syndrome and their families. The program is a subspecialty of the Developmental Medicine Center.

From their first visit at Boston Children’s, new parents work with a team of professionals committed to supporting all of their child’s clinical, physical and emotional needs. We provide specialized medical care, resources, support and advocacy for children with Down syndrome from birth through age 22 and regularly make referrals to other specialty clinics at Boston Children's, depending on a child’s needs. We also help put parents in touch with other families with Down syndrome and connect them to community and educational services appropriate for their child.

For children born with heart defects, our Heart Center is the largest in the United States and one of the most specialized in the world. We provide a full range of care and our specialists have extensive experience treating rare heart problems with results that are among the best in the world.

Support for expecting parents who receive a prenatal diagnosis of Down syndrome

The Down Syndrome Program works closely with the Maternal Fetal Care Center. Depending on a family’s needs, we provide prenatal consultation to answer questions and help expecting parents learn more about Down syndrome. We offer confidential, non-directive counseling for families uncertain about their plans, providing a safe opportunity to gather information and make an informed decision about the pregnancy.

For families with a likely or confirmed diagnosis who plan to continue the pregnancy, the prenatal visit becomes the first clinical visit where we begin to help plan for the baby’s future. We discuss common medical conditions, developmental issues, education and resources in the community.