For many patients, pregnancy can be scary. The uncertainty of not knowing if their baby is healthy can ellicite feelings of anxiety. Reviewing the available testing options for these patients; whether it is for Down syndrome or a family history of a genetic disorder can help put these fears to rest and allow the pregnancy to be less stressful. Knowing if the baby is healthy or not can also reduce the chance of surprises in the delivery room or immediately after birth. Having information on any potential problems with the baby will allow for everyone to be prepared to provide the optimal care at the appropriate time and at the appropriate facility.
Genetic counseling is available to all pregnant women. If you are interested in reviewing all testing options and your family history, you are older than 35 years old at delivery, you have an increased risk on serum screening, there is a family history of a genetic condition or birth defect, or there are ultrasound findings identified in your pregnancy, we are happy to walk through all available testing options that can occur during pregnancy and after delivery.
We strongly believe that genetic testing is an option. We recognize that for some families genetic testing is less important and those decisions are also honored. The goal of the genetic counselors is to tailor the testing options to the specific needs and desires of each patient and her family.
- First trimester screening
- Quad screening
- cell free DNA/Non invasive prenatal testing (NIPT)
- Carrier screening
- Testing after delivery
Ultrasound is used throughout pregnancy for many reasons. Using sound waves, we can “see” pictures of your baby and the pregnancy. With these detailed views, most major birth defects can be seen. We can also look for signs of chromosomal or genetic changes. By diagnosing problems as early as possible, we give future parents up-to-date information and, ideally, improve the outcome for the baby.
Between 11-14 weeks of pregnancy ultrasound can confirm the due date, the number of babies, and measures an area in the back of the baby’s neck, called the nuchal translucency. If the nuchal translucency is big, the pregnancy is at higher risk for chromosomal or genetic changes and birth defects. If a bigger nuchal translucency is identified, we will offer genetic counseling to discuss the risks and the testing options that are available.
We recommend that all pregnant women have at least one ultrasound at 18 to 20 weeks of pregnancy to look at fetal growth and development. At this ultrasound we are assessing for major birth defects and other problems. Ultrasound is extremely valuable for assessing the due date, the number of fetuses, the amniotic fluid, the cervix, the growth of the baby, and the anatomy of the baby. In addition to assessing for major birth defects or other problems, this ultrasound can usually identify the sex of the baby.
First trimester screening is a test is performed between 11 and 14 weeks of pregnancy. The test can identify 80 percent of pregnancies with certain chromosome changes. First trimester screening begins with the nuchal translucency ultrasound and combines this measurement with a blood test to calculate the risk for the two most common chromosome changes, Down syndrome and trisomy 18. If the test results are “positive” it does not mean there is a 100% chance the baby has a chromosome change; rather it means there is a higher chance than expected that a chromosome change could be occurring. With a “positive” result, genetic counseling will be offered to discuss the results and additional testing options. A “negative” test does not eliminate the chance that the baby has a chromosome change.
Advantages of first trimester screening are that it is proven to be a sensitive test for Down syndrome and trisomy 18 screening, it is done early in pregnancy, it has no risk to the baby, and is regularly covered by most insurances.
If you are late to prenatal care or did not have earlier screening (such as first trimester screening), a blood test can be performed in the second trimester to screen for Down syndrome, trisomy 18, and open neural tube defects. This test is commonly called the “quad” screen because it tests four different markers in the blood. This test detects approximately 80 percent of babies with Down syndrome. If the test results are “positive” it does not mean there is a 100% chance the baby has a chromosome change; rather it means there is a higher chance than expected that a chromosome change could be occurring. With a “positive” result, genetic counseling will be offered to discuss the results and additional testing options. A “negative” test does not eliminate the chance that the baby has a chromosome change.
In general, we recommend first trimester screening or cfDNA instead of second trimester screening when possible. Usually insurance regularly covers quad screening for pregnant women.
Cell free DNA screening goes by many names such as non-invasive prenatal testing (NIPT) or non-invasive prenatal screening (NIPS)-these all refer to the same test. cfDNA screening uses a blood draw from the mom to identify pregnancies at increased risk for three chromosome changes: Down syndrome, trisomy 18, and trisomy 13. This test can identify close to 80-99% of pregnancies with these three conditions. The test is available as early as 10 weeks and can be drawn in the second and third trimesters, as well. When cfDNA screening is drawn in the first trimester, we recommend it is done along with the nuchal translucency ultrasound. cfDNA screening is a complicated test and may not be the right test for everyone. Please talk to your provider about this option.
If the test results are “positive” it does not mean there is a 100% chance the baby has a chromosome change; rather it means there is a higher chance than expected that a chromosome change could be occurring. With a “positive” result, genetic counseling will be offered to discuss the results and additional testing options. A “negative” test does not eliminate the chance that the baby has a chromosome change.
Advantages of cfDNA screening are that it is proven to be the most sensitive test for Down syndrome screening in pregnancy, has lower false positive and false negative rates compared to other screening options, it can be done early in pregnancy, and carries no risk to the baby. cfDNA screening does have a higher test failure rate compared to other blood based screening options. Additionally, cfDNA is not reguarlly covered by all insurances. If you have questions about cost related to cfDNA, please call Ariosa directly as we will not be able to provide answers about out of pocket costs related to your insurance plan.
It is important to know that with any genetic test it is possible the results could give us health information on the person tested and not just give us information about the health of the pregnancy.
Experts believe that we are all carriers of genetic disease. Most of the time being a carrier does not cause any health concerns. This means we cannot rely on a normal personal history or family history as reassurance. However, when both partners are a carrier of the same disease they have a 1 in 4 (25%) chance to have a child who could have lifelong health issues. The chance that both you and are partner are carriers for the same recessive disease is less than 2%.
Carrier screening is a blood draw that is performed on one or both parents to determine if that person is a carrier of a recessive disease. Carrier screening is able to detect many, but not all, carriers of disease.
If results are “positive” to be a genetic disease carrier, genetic counseling will be offered to discuss the test results and additional testing options. We will most likely offer carrier screening to your partner. If results are “negative”, the chance to be a carrier of certain genetic diseases is much lower. Generally, no follow-up testing is recommended if the results are “negative”. However, it is important to know that no screen is able to identify every carrier of every disease or all birth defects.
Carrier screening may be useful for families who are concerned about having a child with a genetic condition, for parents who are adopted or do not know much about their family history, or for families who may want more information to help prepare for the birth of a child.
It is important to know that with any genetic test it is possible the results will also give us health information on the person tested and not just give us information about the health of the pregnancy.
Diagnostic testing options:
Diagnostic tests can specifically answer the question of whether a baby has a certain chromosome condition or genetic syndrome. These tests are invasive and carry a risk for miscarriage. We can test for many conditions with diagnostic testing, including Down syndrome, but these tests are generally reserved for those couples that have a known risk factor for a specific condition.
If you are in a risk group for which a diagnostic test may be indicated, genetic counseling will be offered to ensure that you are informed about the risks, benefits, and limitations of these procedures, as well as, any alternative testing options.
It is important to understand that no test can identify all birth defects or genetic conditions prior to delivery.
Chorionic villus sampling, or CVS, takes a piece (biopsy) of the developing placenta. It is done either though the mother’s cervix or through her abdomen. The procedure is performed by our experienced doctors and ultrasound is used for guidance during the entire procedure. The test is typically performed from 10 through 13 weeks of pregnancy and allows for the examination of the chromosomes or other genetic syndromes. The procedure related risk of miscarriage is less than 1%.
Amniocentesis is a sampling of the amniotic fluid around the baby by inserting a thin needle through the mother’s abdomen. The procedure is performed by our experienced doctors and ultrasound is used to guide the needle during the entire procedure. The fluid obtained allows for the examination of fetal chromosomes or other genetic syndromes. The fluid is also tested to screen for open neural tube defects (spina bifida). Amniocentesis is typically performed at 15-20 weeks of pregnancy and carries a risk of miscarriage of less than 1%.
Genetic testing can also be performed after delivery through a blood draw. You will be offered to meet with our pediatric geneticist to make a plan for genetic testing after delivery. Genetic testing can help guide the care and management of your baby.