What Is Down Syndrome?

Down syndrome, also called Trisomy 21, occurs when a baby has three copies of chromosome 21 instead of the typical two. It is the most common chromosomal condition, occurring in approximately 1 in every 700 births in the United States. It is not caused by anything a parent did or did not do during pregnancy.

Down syndrome affects each person differently. Some individuals have mild developmental differences and live with a high degree of independence. Others need more support. There is no way to predict exactly where on the spectrum a child will fall based on a prenatal diagnosis alone.

How It Is Detected During Pregnancy

Screening

Most prenatal screening pathways can flag an elevated probability of Down syndrome:

  • First-trimester combined screening (blood work plus nuchal translucency ultrasound) at 11 to 14 weeks
  • NIPT (cell-free DNA) at 10+ weeks, with a detection rate above 99% for Trisomy 21
  • Quad screen (second-trimester blood work) at 15 to 22 weeks

A positive screening result does not mean your baby has Down syndrome. It means the statistical risk is elevated and diagnostic testing can provide a definitive answer.

Diagnostic Confirmation

Only CVS (10 to 13 weeks) or amniocentesis (15 to 20 weeks) can confirm or rule out a Down syndrome diagnosis. These tests analyze the baby's actual chromosomes and are more than 99% accurate.

The Range of Outcomes

Down syndrome is not a monolith. The range of abilities, health needs, and life experiences among people with Down syndrome is wide. Understanding this range is essential before making any decisions.

Cognitive and Developmental

Most individuals with Down syndrome have mild to moderate intellectual disability. With early intervention services, many children reach developmental milestones that were considered unlikely just a generation ago. Reading, writing, holding jobs, and living semi-independently are common realities for adults with Down syndrome today.

Medical Considerations

About 50% of babies with Down syndrome are born with a congenital heart defect, many of which are correctable with surgery. Other conditions that occur more frequently include:

  • Thyroid dysfunction, which is typically manageable with medication
  • Hearing loss, affecting roughly 75% of individuals to some degree
  • Vision issues, including strabismus and refractive errors
  • Gastrointestinal differences, seen in about 12% of babies
  • Increased susceptibility to respiratory infections in early childhood

Regular medical monitoring addresses most of these conditions effectively, and specialized care guidelines exist through the American Academy of Pediatrics.

Life Expectancy

Life expectancy for people with Down syndrome has increased dramatically over the past several decades. In 1983, the average life expectancy was 25 years. Today, it exceeds 60 years, with many individuals living into their 70s. This shift reflects advances in cardiac care, early intervention, and inclusive education.

The Decision Landscape

A prenatal diagnosis of Down syndrome places families at a crossroads, and there is no single right path. Some families continue the pregnancy and prepare for a child with different needs. Others make a different choice. Both decisions are deeply personal and deserve compassion and respect.

What matters most during this time:

  • Get complete information. The picture painted by a brief conversation in a clinical setting is rarely the full story. Connecting with a genetic counselor, reading current resources, and speaking with families who are raising children with Down syndrome can provide perspective that clinical data alone cannot.
  • Take your time. Unless there is a medical urgency, you do not need to make decisions immediately. Give yourself space to process.
  • Seek support. Organizations like the National Down Syndrome Society (NDSS) and local parent networks offer judgment-free support for families at every stage of the decision-making process.
  • Talk to your partner and your care team. You do not have to navigate this alone.

What Support Looks Like

If you continue the pregnancy, early preparation can make a meaningful difference. Many families benefit from:

  • Connecting with early intervention programs before birth
  • Building a pediatric care team that includes specialists familiar with Down syndrome
  • Joining local or online parent communities
  • Learning about educational rights and services through programs like Early Intervention (birth to 3) and IDEA (3 and up)

Finding Your Care Team on BAABY

If you have received a prenatal diagnosis of Down syndrome or are navigating screening results, having the right care team around you matters. BAABY's provider directory can help you find OB-GYNs and maternal-fetal medicine specialists who can guide you through this process with compassion and clinical expertise.