Down Syndrome: Symptoms and Early Signs
The early signs and symptoms of Down syndrome are often caught in screening and testing during pregnancy. This article breaks down the diagnostic process.
By Ability Central
12 April, 2023
Each year about 1 in every 700 babies born in the United States has Down syndrome. In this article, Ability Central will share the early signs and symptoms of the condition, including:
- What early signs do doctors look for to test for Down syndrome during pregnancy?
- What screening tests are used during pregnancy to determine the likelihood of the baby being born with Down syndrome?
- What is the difference between a prenatal screening test and a diagnostic test?
- What tests are used to verify Down syndrome after birth?
- Is Down Syndrome inherited?
- Where can I get more information about Down syndrome?
What early signs do doctors look for to test for Down syndrome during pregnancy?
The American College of Obstetricians and Gynecologists recommends offering screening tests and diagnostic tests for Down syndrome to all pregnant women, regardless of age.
Generally, the chance of having a baby with Down syndrome is related to the pregnant woman's age. The National Down Syndrome Society (NDSS) says the incidents of Down syndrome by age are as follows:
- At 20 years old, Down syndrome occurs in 1 in 2,000 births.
- At 25 years old, the rate increases to 1 in 1,200.
- At 30 years old, the rate is 1 in 900.
- At 35 years old, the rate is 1 in 350.
- At 40 years old, the rate is 1 in 100.
- At 45 years old, the rate is 1 in 30.
- By 49 years old, the rate is 1 in 10.
What screening tests are used during pregnancy to determine the likelihood of the baby being born with Down syndrome?
As mentioned in Down Syndrome: Seven Quick Facts You Should Know, Down syndrome testing can be broken into screening tests and diagnostic tests.
Screening tests may include blood tests or ultrasounds. These tests show the likelihood of the baby being born with Down syndrome. Blood tests and ultrasounds have very little risk.
The first trimester combined test is broken into two parts. First, a blood test measures the levels of pregnancy-associated plasma protein-A (PAPP-A) and the pregnancy hormone, human chorionic gonadotropin (HCG). Abnormal levels of PAPP-A and HCG may indicate a problem with the baby. Then, an ultrasound measures the fluid at the back of the baby’s neck. The doctor combines these two tests with the mother's age to estimate your risk of having a baby with Down syndrome.
What is the difference between a prenatal screening test and a diagnostic test?
Diagnostic tests can confirm a Down syndrome diagnosis if the screening tests are positive or worrisome. According to the Cleveland Clinic, diagnostic testing offers more risk for both the birthing parent and the developing fetus. These tests may include the following:
- Chorionic villus sampling (CVS)
- Percutaneous umbilical blood sampling (PUBS)
Both amniocentesis and CVS are safe, but they do have a slight risk of causing a miscarriage. PUBS has a slightly higher risk of causing serious problems than amniocentesis or CVS.
To understand the reliability and risks of these tests, see Down Syndrome: First Steps After Diagnosis.
What tests are used to verify Down syndrome after birth?
After birth, Down syndrome is often initially diagnosed based on the baby's appearance. Because the physical features may be present in babies without Down syndrome, a chromosomal analysis called a karyotype is done to confirm the diagnosis. To learn more, see the National Down Syndrome Society (NDSS).
Is Down syndrome inherited?
Couples who have had one child with Down syndrome have a slightly increased risk of having a second child with Down syndrome.
Only 1% of all cases of Down syndrome have a hereditary component. According to the National Down Syndrome Society (NDSS), the risk of recurrence of translocation Down syndrome is about 3% if the father is the carrier and 10-15% if the mother is the carrier.
Where can I get more information about Down syndrome?
Ability Central offers a series of articles to further your knowledge about Down syndrome. See:
- Down Syndrome: Seven Quick Facts You Should Know
- Down Syndrome: First Steps After Diagnosis
- Down Syndrome: Planning for Long-term Care