You have arrived at this page because your doctor has recommended screening or may suspect that the child you carry – or being carried by a friend or loved one – may have Down syndrome.
You are likely troubled. We would like to offer hope where many people see none.
We hope because the only thing we all know for sure is that a baby is on the way and babies are all packages of everything in life just waiting to happen.
For now, let’s focus on the facts.
There are several types of screenings that your doctor may recommend. Screens are not tests nor are they diagnostic in nature. They are only used to determine whether further, more invasive, testing is necessary. You should know that any screening or test are optional and are your choice to have done.
- Quad Screen, offered between fifteen and twenty weeks. This simple blood test is recommended for all pregnant women, regardless of age. This test measures levels of pregnancy-associated plasma protein-A and the pregnancy hormone knows as human chorionic gonadotropin. This screen will give a statistical risk of various chromosomal conditions, and yields a 69%-81% accurate positive rate.
- Cell-Free DNA screen (brand names include MaterniT21, Verifi, Panorama), can be offered as soon as 10 weeks gestation. This non-invasive blood test relies on the detection of cell-free DNA that circulates between the fetus and the expectant mother. This screen yields up to a 98.6% accurate positive rate.
- Ultrasound, offered around ten to fourteen weeks is also common. The ultrasound is used to check for physical features that may be associated with Down syndrome, and may be used in conjunction with a blood test.
Again, the screens will not give you definitive answers; they give you a probability that your baby may have Down syndrome. Further testing will be necessary to give you a yes or no for a diagnosis of Down syndrome.
If the screening test results show there is a high level of probability that your child may have Down syndrome, an invasive, diagnostic test, typically done in consultation with a genetic counselor, will be recommended.
There are two such tests which are typically recommended – a chorionic villus sampling (CVS) and amniocentesis. These procedures, which carry up to a 1% risk of causing a spontaneous miscarriage, are nearly 100% accurate in diagnosing Down syndrome.
- Amniocentesis: A sample of the amniotic fluid surrounding the fetus is withdrawn through a needle inserted into the mother’s uterus. This sample is then used to analyze the chromosomes of the fetus. Doctors usually perform this test in the second trimester, after 15 weeks of pregnancy. This test carries a slight risk of miscarriage, which increases if it’s done before 15 weeks.
- Chorionic Villus Sampling (CVS): In CVS, cells are taken from the placenta and used to analyze the fetal chromosomes. It is typically performed in the first trimester after 10 weeks of pregnancy. This test appears to carry a somewhat higher risk of miscarriage than second trimester amniocentesis.
Please visit Mayo.com for more information about each of these tests and screens.
Why Should I Get a Prenatal Test?
Some mothers choose to forgo all diagnostic testing because they know that they would continue their pregnancy no matter what the result and do not want to expose their pregnancy to even the small risk of miscarriage that come with CVS and amniocentesis. Some start with a prenatal screen and then proceed to a definitive diagnostic test. Other mothers simply bypass the prenatal screen and start with a definitive diagnostic test. Whether or not to undergo a prenatal screening or diagnostic test is a personal decision, and expectant parents must make the choice that is best for them.
Will having a baby with Down syndrome change my pregnancy?
There is nothing in the news that changes anything about your pregnancy. Assuming you are healthy, we encourage you to enjoy the coming months.
There are exceptions: Many babies with Down syndrome have cardiovascular and gastrointestinal issues. Some can be detected prenatally, and you should consult with your medical professionals about how they may affect your delivery and your child’s postnatal care.
However, don’t feel pressured into decisions or overloaded on information during your pregnancy.
Go slowly. Gather facts and discuss everything with your spouse or partner, friends, and family. Then, when you are ready, you will be able make an informed choice.
Right now, you cannot know what is relevant to your situation – most isn’t. This is about individuality – all that can be said about Down syndrome are generalities that may not apply to your child or your pregnancy. Please don’t worry now about the future – about where your child might be at 6, 16, or 46. We will provide lifetime support every step of the way.
Down Syndrome: Tests and Diagnosis, www.mayoclinic.org/diseases-conditions/down-syndrome/basics/tests-diagnosis/con-20020948
National Down Syndrome Congress: www.ndsccenter.org
National Down Syndrome Society: www.ndss.org
“You are pregnant” prenatal brochure produced by the Global Down Syndrome Foundation: www.downsyndrometest.org