Down Syndrome is the most commonly occurring genetic birth defect in the United States. (Birth defects occur while the baby is still developing inside the womb.) Prior to or at conception while cells are dividing, an error can happen. When a specific error occurs that results in the baby’s having 47 chromosomes instead of the standard 46, the baby is born with Down syndrome. There are three types of Down syndrome, the most common is known as trisomy 21 (because it’s the 21st chromosome is duplicated).
What kind of prenatal tests are available to detect Down syndrome?
Two types of tests can be performed before a baby is born: screening and diagnostic tests. Most screening tests involve a blood sample from the mother and an ultrasound. The blood sample can check for things in the mother’s blood that provide information about the health of the mother and baby. Screening tests cannot diagnose a birth defect; instead they are used to predict whether a birth defect may be present. That means that a blood sample is not a 100% guarantee; it can only give doctors an idea of what might be happening.
Diagnostic tests include blood tests and the following invasive procedures:
- amniocentesis (a needle inserted through the mother’s abdominal wall into the uterus withdraws a sample amniotic fluid)
- chorionic villi sampling (removing a tiny tissue sample from the placenta either through the mother’s cervix or inserting a needle through the mother’s abdominal wall into the uterus and placenta)
- umbilical cord blood sampling (inserting a needle through the mother’s abdominal wall into the umbilical cord to withdraw blood).
Invasive diagnostic tests have a small chance of causing a miscarriage, bleeding in the uterus or infection.
How accurate are these tests?
Screening tests for genetic disorders can only predict the possibility that the baby may have Down syndrome (doctors may rate the possibilities as high risk, moderate risk or low risk). False positive results are possible (when a test came back positive but the baby had no genetic problems); false negative results are also possible (when a test came back negative but the baby did have a genetic disorder). If you or someone you know has been screened for genetic problems such as Down syndrome, be sure to take time to get more information before making any pregnancy decisions. Invasive diagnostic tests (involving removing samples with a needle) are more accurate than the screening tests.
Talk to your obstetrician!
Obstetricians do routine screening tests (blood tests and ultrasounds) throughout a pregnancy to help detect potential problems. Ask your doctor which procedures will be done and at what point in your pregnancy can you expect these tests. In addition, ask specific questions about the accuracy of the tests. Most doctors need to warn their patients about any potential problems, but we know that once someone hears about the possibility of a negative outcome, processing the difference between possibility and certainty can be hard.
How does Down syndrome affect children and families? What kind of life will they have?
While it is true that people with Down syndrome have an increased risk for certain medical conditions (such as congenital heart defects, respiratory and hearing problems, childhood leukemia and thyroid conditions), many of these conditions are very treatable. Most people lead healthy lives. Life expectancy for someone with Down’s has increased from 25 in 1983 to 60 today.
People with Down syndrome attend school, work, participate in decisions that affect them, have meaningful relationships, vote and contribute to society in many wonderful ways. While all will experience cognitive delays, the effect is usually mild to moderate. And talking only about cognitive delays does not begin to account for the many strengths and talents that each individual possesses. According to the National Down Syndrome Society studies show that families caring for children with Down syndrome do experience additional challenges. However, their levels of well-being are still comparable to those families who do not have a child with Down syndrome, and the positive impacts far outweigh the difficulties or challenges.
“Down syndrome” may not be what you want to hear or hoped to hear. But take a deep breath. Different doesn’t have to be wrong or impossible. The future is still bright, both for the parents and for the baby, and we can help you process the new reality so that you each can thrive to become the persons you are meant to be.