How Does Genetic Testing Work In Pregnancy

Choosing The Best Dna Tests For Genetic Conditions

Advanced prenatal genetic testing

Receiving false results on a genetic screening, such as false-positive or false-negative is not something you want to deal with when it comes to the health of your baby. Its important to seek a test that will give you true results. CVS is not the best place to purchase a DNA test.

You also do not have to meet with a geneticist or genetic counselor for a genetic test. Effective, high-quality genetic tests are available online, but not all of them are created equal.

DNA tests many people know about like 23andMe, MyHeritage, and are great for basic health and ancestry information. The data from those tests can be used to identify some potential genetic disorders, but they are not comprehensive enough to provide as much information as you need.

This means if you use that data, it may miss some very important genetic diseases that you should know. has an Ultimate DNA Test that tests more of the human genome but still doesnt test the entire genome. Again, this means some diseases may be missed in the analysis. The best genetic testing for genetic diseases is whole-genome sequencing.

Due to advancements in technology, its possible to sequence their whole genome. What does that mean? It simply means its able to pull out information for tens of thousands of genes. The analysis of those genes is what produces the test results you need genetic testing during pregnancy.

There’s Power In Being Prepared

Noninvasive prenatal screening gives you important information. Your healthcare provider can help you determine if testing is right for you.

Most women get reassuring results that their pregnancy is at low risk for chromosome abnormalities. If your screen turns up something unusual, your healthcare provider will discuss what it means and will offer a follow-up diagnostic procedure to confirm the results. This may be chorionic villus sampling or amniocentesis.

The Prequel Prenatal Screen is a screening test, not a diagnostic test. This means it cannot give a definitive answer as to whether or not your pregnancy is affected by a chromosome condition. To confirm positive screening results, you will need to have a follow-up diagnostic test or discuss other options with your provider.

Getting The Right Care

Not every parent-to-be chooses genetic testing. Some couples want to deal with situations as they come.

Yet, there are other patients who say, I want to know if my baby has Down syndrome. I want to plan ahead, says Dr. Vander Haar.

If parents choose genetic testing and the baby has a serious condition, Dr. Vander Haar recommends the following:

  • Seek care from a maternal-fetal medicine specialist, a doctor who is trained to manage high-risk pregnancies.
  • Consult with a pediatrician who specializes in the type of care your child will need, such as a pediatric neurologist or cardiologist.
  • Connect with organizations like March of Dimes or the National Down Syndrome Society for information and support, or look for a local parents support group.
  • Plan to give birth in a hospital that has an advanced neonatal intensive care unit . Says Dr. Vander Haar, If there are anatomic abnormalities associated with the genetic condition, youre going to want to deliver where you can get high-level NICU care as well as pediatric surgery.

Emilie Vander Haar, M.D., is an ob-gyn, maternal-fetal medicine specialist, and associate director of OB Ultrasound and Prenatal Testing at NewYork-Presbyterian Alexandra Cohen Hospital for Women and Newborns, with expertise in high-risk obstetrics. She is also an assistant professor of obstetrics and gynecology at Weill Cornell Medicine. Dr. Vander Haar specializes in obstetric ultrasound and prenatal diagnostic procedures.

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What Is Prenatal Genetic Testing

Prenatal genetic testing gives parents information about genetic disorders or birth abnormalities the fetus may have. Unlike some of the routine prenatal tests like blood type, blood count or glucose screening, these tests are optional. Talk with your healthcare provider and decide which tests are right for you.

Some people decide to get prenatal genetic testing in addition to routine pregnancy testing. Prenatal genetic testing is optional. A persons chromosomes or genes cause genetic disorders. A gene is part of your bodys cells that stores instructions for how your body works. A chromosome holds your genes. Congenital disorders are present at birth, and healthcare providers can diagnose some of these conditions before birth.

There are two different kinds of tests: screening tests and diagnostic tests.

Types Of Genetic Screenings And Diagnostic Testing During Pregnancy


Genetic Blood TestA genetic blood test is available to women to provide screening for some disorders. Screening tests alone are not diagnostic. If a blood test finds a possible problem, a prenatal diagnostic test may be recommended to confirm a diagnosis. These diagnostic tests include chorionic villus sampling or amniocentesis and are used to perform fetal chromosome analysis or microarray analysis of fetal cells.

Chorionic Villus Sampling Chorionic villus sampling is a diagnostic test usually performed between the 10th to 12th weeks of pregnancy. The perinatologist gently suctions a small piece of the placenta on the outside of the fetal sac to obtain fetal tissue and cells in order to look at fetal chromosomes and/or DNA, and potentially other genetic conditions in the fetus.

AmniocentesisA genetic amniocentesis is a diagnostic test usually performed between weeks 16 to 20 of a womans pregnancy. The perinatologist inserts a hollow needle to remove a small amount of amniotic fluid from around the developing fetus. This fluid has fetal cells floating in it that allow the laboratory to study fetal chromosomes by routine analysis or by microarray, as well as to obtain fetal DNA for other types of genetic testing depending on the family history. This fluid also allows testing for neural tube defects or abdominal wall defects in the developing fetus.

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What Screenings Are Done In The First Trimester

The first-trimester serum screening, cell free fetal DNA screening and the NT ultrasound exam all occur at 11 to 14 weeks of pregnancy. Combining information from the blood tests with the ultrasound findings indicates how high the risk is for some common chromosomal disorders, like Down syndrome.

You can have carrier screenings at any point during your pregnancy, even as early as 6 to 10 weeks gestation. These tests check for single gene genetic conditions that you can potentially pass to the fetus. Carrier screening wont identify conditions due to abnormal chromosome numbers, like Down syndrome.

Cell-free fetal DNA testing checks your blood for fetal DNA. It looks for chromosomal conditions like Down syndrome, trisomy 13 and trisomy 18. Your provider can perform this screening as early as 10 weeks gestation, or later during pregnancy.

Prenatal Genetic Screening Tests

Prenatal screening for rare diseases can identify gene mutations that may be passed on to a baby. If a prenatal test identifies you are a carrier of a disease, genetic counselors often recommend testing the father to see if he is also a carrier.

While someone can suffer from disease by inheriting a single gene, theres a much higher risk when the person receives two gene mutations for the disease. This is because there are two genes associated with a disease, and if one is mutated, the other can protect the person from the disease by picking up the job of the other one.

If carrier screening shows an elevated risk for a genetic disease like Tay-Sachs or something else, prenatal care may be recommended to lower the risk for the fetus.

Learn More: Carrier Screening

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Getting Support And Advice

Planning a pregnancy can cause a lot of worry if you are concerned about a genetic condition that can be passed on to your children. The results of a genetic test can have a major impact on your life and the lives of your family members. You should consider talking to your doctor or getting genetic counselling before going ahead with testing.

Whats The Best Dna Test Kit

Genetic Testing During Pregnancy

You should try to find a provider or genetic counselor near you to perform DNA testing. They will order the correct tests and then talk to you about what they mean. But if you cant go through your healthcare provider, you can get a DNA test kit directly from a DNA testing company. These test kits are called direct-to-consumer genetic tests. The best DNA test kits offer easy-to-understand information about the scientific basis of their tests, but it is risky to use them because there may not be anyone you can speak to personally about the results.

If you test positive for a genetic condition or find that you have a higher risk of developing a disease, you should call your healthcare provider. They can put you in touch with a genetic counselor who can evaluate you and the information you have and help you decide what to do next.

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If You Receive A Positive Result

If you receive positive results on a screening test, we recommend that you discuss this with your doctor and a genetic counselor. Options for further diagnostic testing will be explained. The decision as to whether to have invasive genetic testing is up to you.

If a diagnostic test finds a genetic abnormality, the significance of such results should be discussed with experts familiar with the condition, including a medical geneticist and a genetic counselor, as well as your own doctor.

UCSF Health medical specialists have reviewed this information. It is for educational purposes only and is not intended to replace the advice of your doctor or other health care provider. We encourage you to discuss any questions or concerns you may have with your provider.

Video: Screening For You And Your Baby

This video shows which tests are available during pregnancy and after your baby has been born.

You can watch translated versions of this video on Vimeo.

You’ll be offered some screening tests during pregnancy to try to find any health conditions that could affect you or your baby.

The tests can help you make choices about further tests and care or treatment during your pregnancy or after your baby’s born. All screening tests offered by the NHS are free.

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Common Feelings About Testing

Not everyone who has genetic testing or screening will have the same reaction. People within a family may have very different feelings.

  • Some people may worry about what the test result may show, or how they will react to the test result.
  • Others may feel relief that they were able to inform themselves. The results of genetic testing may help these people decide what to do next.
  • People who are at risk of having a child with a genetic condition may feel anxious or overwhelmed at the thought of passing it onto the next generation.
  • Others may be comfortable with the risks but want to learn about their options.
  • People undergoing fertility treatments or prenatal testing may feel stress because of the risk of the procedures, the decisions that they may face, the future health of their baby, financial strain, and relationship pressures.

Whats A Dna Paternity Test

Figure 1 from Noninvasive prenatal testing for fetal aneuploidy and ...

A DNA paternity test can determine whether a person assigned male at birth is another persons biological father. You can determine whether someone could be the biological father of your baby or child through a DNA cheek swab or blood test. Paternity tests can also be done using a prenatal paternity test during pregnancy.

A note from Cleveland Clinic

DNA tests can help you determine if you have a genetic condition or if youre more likely to develop one. Genetic testing may give you peace of mind, but it also comes with many risks and limitations. If youre interested in taking a genetic test, call your healthcare provider. They can refer you to a genetic counselor to give you more information about the process.

Last reviewed by a Cleveland Clinic medical professional on 05/21/2022.


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How Does Someone Get Genetic Testing

If someone decides they want genetic testing, they meet with a genetic counselor. The counselor can help them decide what tests to get and to understand the test results. They can talk about different options and offer support and resources.

After talking to a genetic counselor, some people decide not to do genetic testing. It may be too expensive or cause too much worry. Othes might decide not to do it because they dont want to know or its not going to change any decisions they make. There is no right or wrong answer about who should get genetic testing.

What Type Of Tests Are Used

If you decide to get prenatal genetic testing for SMA, the type of test will depend on the stage of your pregnancy.

Chorionic villus sampling is a test thats done between 10 and 13 weeks of pregnancy. If you get this test, a DNA sample will be taken from your placenta. The placenta is an organ thats only present during pregnancy and provides the fetus with nutrients.

Amniocentesis is a test thats done between 14 and 20 weeks of pregnancy. If you get this test, a DNA sample will be collected from the amniotic fluid in your uterus. Amniotic fluid is the liquid that surrounds the fetus.

After the DNA sample is collected, it will be tested in a laboratory to learn if the fetus has the gene for SMA. Since CVS is done earlier in pregnancy, you will get the results at an earlier stage of your pregnancy.

If the test results show that your child is likely to have the effects of SMA, your doctor can help you understand your options for moving forward. Some people decide to continue the pregnancy and explore treatment options, while others may decide to end the pregnancy.

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What Genetic Tests Are Available For Cancer Risk Assessment

More than 50 hereditary cancer syndromes have been described see the PDQ Cancer Genetics Overview for a list of familial cancer susceptibility syndromes. Most of these are caused by harmful variants that are inherited in an autosomal dominant fashionthat is, a single altered copy of the gene inherited from one parent is enough to increase a persons chance of developing cancer. For most of these syndromes, genetic tests for harmful variants are available.

Tests are also available for several inherited genetic variants that are not associated with named syndromes but have been found to increase cancer risk. Examples include inherited variants in PALB2 , CHEK2 , BRIP1 , and RAD51C and RAD51D .

Who Might Want To Get Genetic Testing

Genetic Testing: How it Can Help During Your Pregnancy

People get genetic testing for many reasons. Pregnant women often get genetic testing on their blood as part of their regular prenatal care.

Someone might get genetic testing to:

  • Learn if they have a genetic illness that runs in their family.
  • See if a current pregnancy is affected by a genetic illness.
  • Learn what the risk is for a future pregnancy to be affected by a genetic illness.
  • See if they are a carrier for a genetic illness.
  • Guide treatment plans for certain genetic illnesses.
  • See if a child has a genetic illness.

People with a higher risk for having a child with a genetic illness may want genetic testing. This includes:

  • families with genetic illnesses in close relatives
  • parents who already have a child with a genetic illness
  • couples who plan to start a family and one of them or a close relative has a genetic illness
  • pregnant women over age 34 or who have an abnormal prenatal screening test or amniocentesis
  • women who have had two or more miscarriages, or delivered a stillborn baby with physical signs of a genetic disorder

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What Is Amniocentesis

In this test, a small amount of amniotic fluid will be taken out of the uterus with a needle inserted through your abdomen. The doctor will use ultrasound to guide the needle to an area far from the baby. Some of the babys cells will be present in the fluid. These are extracted and tested for genetic abnormalities. This test has a low risk of miscarriage of 0.5% -1%. If you have a fetus diagnosed with a genetic abnormality, you have the choice of continuing or terminating the pregnancy.

Dna Testing For Fetus

Your BGYN might recommend you undergo additional screening if you have one of the following:

  • Abnormal prenatal screening test result. If you receive an abnormal prenatal screening test result, a genetic test might be necessary to help detect the genetic condition.
  • Prior history of inherited illness. Genetic testing can help you plan on whether to start a family when you have a close relative or a partner with inherited illness.

Remember some people might be a carrier of a genetic disorder have genetic defects but dont show clinical signs and symptoms. In this situation, your baby will only show symptoms if he/she inherits two copies of defective genes .

  • Have a child with a serious birth defect. While having a baby with a genetic defect doesnt always mean you give birth to a child with a genetic problem, it is important to do a genetic test. Some of the birth defects are not inherited meaning you will have a baby in your next pregnancy. Sometimes the cause could be a spontaneous error in the cells of your child and not your cells or your partner.
  • Having miscarriages. Chromosomal abnormalities in your fetus can lead to pregnancy loss. Having more than 2 miscarriages might point to a genetic problem.
  • Having stillbirth with visible signs of a genetic condition. Genetic testing is recommended to help identify any genetic problems that could have caused physical problems.

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