Pros And Cons Of Genetic Screening
“Every woman wants to believe that her pregnancy is normal and uncomplicated,” Greiner told Live Science. If a pregnant woman chooses to have genetic screening, there is a possibility that the results could come back abnormal so it’s important to think about how this information might affect her, she noted.
But not all genetic screening occurs while a woman is expecting. In some situations, it may be done before becoming pregnant. For example, during pre-conception genetic screening, carrier tests can be done to determine whether the mother or father carry a certain gene for genetic disorders that might run in families, such as cystic fibrosis and sickle cell anemia, and could be passed on when the couple conceives.
A common misconception among some pregnant women is that the only reason to do genetic screening and diagnostic testing is if they were going to have an abortion because of a positive result, Greiner said. But that’s not the case, she said.
Whether or not a woman decides to undergo genetic screening is her own choice, as positive results could produce anxiety and conflicting emotions. Another disadvantage is that genetic screenings can give false positive results, meaning they can be wrong and lead expectant parents to believe their unborn babies might have genetic abnormalities when they do not. There’s also a chance the screening will not pick up a chromosomal abnormality or birth defect when there is one.
What Is Genetic Testing
Genetic testing helps to find out if a persons genes or chromosomes may be linked to a health condition it can also identify changes in a persons genes. The procedure can be done before a pregnancy, during a pregnancy, or later in life.
Genetic testing is not available for every condition. It is also not usually possible unless the gene change is already known in the family. Lastly, results of the testing are not always clear. Because of these and other limitations with genetic testing, and because not all health conditions are genetic, a normal result does not guarantee that a child will be healthy.
A: Screening Results Using Enhanced First Trimester Screening As An Example:
Enhanced First Trimester Screening calculates the chance that the baby has Down syndrome or trisomy 18. It does not screen for open neural tube defects or any other condition. eFTS uses the age of the pregnant person/egg donor at the time of delivery, the size of the nuchal translucency on a first trimester ultrasound, and the levels of certain hormones in the pregnant persons blood that are being produced by the current pregnancy. A risk is then calculated estimating the chance that the baby has either condition. Generally, for eFTS, a risk greater than 1/350 is considered screen positive and any risk lower than this is a screen negative. For more on eFTS see AFTER: The next steps
What if my eFTS result is a screen NEGATIVE?
This is reassuring. This means that the chance that your baby has Down syndrome or trisomy 18 is LOWER than the screening cut-off . Note that the screening cut-off may vary by laboratory and condition.
What do I do next?
What if my eFTS result is a screen POSITIVE?
This means that the chance of your baby having Down syndrome or trisomy 18 is HIGHER than the screening cut- off . This result does not necessarily mean that your baby has one of these genetic conditions. Remember that most babies are born without an anomaly.
A nuchal translucency measurement greater than 3.5 mm is an automatic screen positive for Down syndrome and certain other disorders and should prompt a referral for genetic counselling.
Is an eFTS screen POSITIVE result accurate?
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What Are Some Of The Most Common Genetic Diseases
Cystic Fibrosis
Cystic fibrosis is a life-threatening condition that causes lung damage and digestive problems. About 30,000 people in the U.S. have the disease, which mostly affects Caucasians of Northern European descent. Organizations like the National Institutes of Health, the American College of Obstetricians and Gynecologists, and the American College of Medical Genetics have recommended nationwide genetic testing for CF for all adults since 2002. According to a recent study in the New England Journal of Medicine, the number of babies born with cystic fibrosis in Massachusetts dropped by about 50 percent in the four years after this recommendation was made and testing came into wider use compared to the four years before.
Sickle Cell Disease
This genetic condition is most common in people of African and Mediterranean backgrounds, causes a blood disorder that leads to anemia, a weakened immune system, and other health complications.
Thalassemia
Thalassemia is another blood disorder common to people of African and Mediterranean descent. It typically causes anemia and bone growth and liver problems in severe cases, some babies born with the condition may not survive.
Tay-Sachs Disease
Fragile X Syndrome
What Are Screening Tests
Screening tests are used to find people at higher chance of a health problem.
This means they can get earlier, potentially more effective, treatment or make informed decisions about their health.
Screening tests are not perfect. Some people will be told that they or their baby have a higher chance of having a health condition when in fact they do not have the condition.
Also, a few people will be told that they or their baby have a lower chance of having a health condition when in fact they do have the condition.
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What About Genetic Counselling
The information obtained from genetic testing can have a profound impact on your life. Genetic counselling is available to anyone undergoing, or thinking of undergoing, any form of genetic testing. Genetic counselling is not a psychological therapy. It aims to provide you with all the information you need to make a decision about whether you should have a genetic test.
Genetic counselling may include information about:
- The implications of testing positive for the genetic disorder, including the psychological impact and other consequences.
- Whether to inform relatives of your intention to test, or not to test.
- The usual pattern of progression of the disease you are being tested for and its potential treatments.
The information is given in a way that will allow you to make your own decision. Only you can decide what is right for you. The counselling is essential to make sure you have all the information you need to make the decision.
As they consider the options available to them, people are influenced by:
- The risk of transmitting a disorder.
- The severity of a disorder.
- The availability of diagnosis before birth .
- Moral, social and religious convictions.
Post-test counselling is also available to help you deal with the results of the test.
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 .
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Most Common Genetic Disorders
Cystic Fibrosis
Cystic fibrosis is a life-threatening condition that causes lung damage and digestive problems. About 30,000 people in the U.S. have the disease, which mostly affects Caucasians of Northern European descent. Organizations like the National Institutes of Health, the American College of Obstetricians and Gynecologists, and the American College of Medical Genetics have recommended nationwide genetic testing for CF for all adults since 2002. According to a recent study in the New England Journal of Medicine, the number of babies born with cystic fibrosis in Massachusetts dropped by about 50 percent in the four years after this recommendation was made and testing came into wider use compared to the four years before.
Sickle Cell Disease
This genetic condition is most common in people of African and Mediterranean backgrounds, causes a blood disorder that leads to anemia, a weakened immune system, and other health complications.
Thalassemia
Thalassemia is another blood disorder common to people of African and Mediterranean descent. It typically causes anemia and bone growth and liver problems in severe cases, some babies born with the condition may not survive.
Tay-Sachs Disease,
Fragile X Syndrome
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.
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Do I Have To Have Screening
No it’s up to you whether you have a screening test. It’s a personal choice that only you can make.
You can discuss each of the screening tests you’re offered with your midwife or doctor and decide whether or not it’s right for you.
Some of the screening tests you’ll be offered are recommended by the NHS.
These include:
- blood tests for infectious diseases
- eye screening if you have pre-existing diabetes
- newborn screening tests
This is because the results from these tests can help make sure that you or your baby get urgent treatment for serious conditions.
What Other Tests Are Done In The First Trimester
After the first visit, you can expect to get your urine tested and your weight and blood pressure checked at every visit until you deliver. These tests can find problems such as gestational diabetes and preeclampsia .
During your first trimester, you’ll be offered more tests depending on your age, health, family medical history, and other things. These can include:
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A Guide To Genetic Testing Before & During Pregnancy
Find out what genetic testing is, and whether you and your partner should get tested before you get pregnant.
Genetic testing is when a blood test is given to prospective or expecting parents to look for abnormal genes that can lead to certain diseases in their baby. Most genetic diseases are known as “recessive disorders,” which means that each parent needs to pass along an affected gene to the baby in order for the child to be affected.
In other words, if you screen positive for a genetic abnormality but your partner does not, your child will not inherit the condition. And even if you both screen positive, there’s only a 25 percent chance your baby will have the disease.
What Are Kick Counts And How Do You Do Them
Kick counts is a way for you to track how often your baby moves. By about 5 months of pregnancy, you should start to feel your baby move in your belly. Your baby can turn from side to side and sometimes head over heels. Tell your provider if:
- Youre at about 20 weeks of pregnancy and havent felt your baby move.
- Youre worried that your baby isnt moving.
- You notice a change in how often your baby moves, especially if movement decreases.
Your provider may ask you to do kick counts to see when and how often your baby moves. Here are 2 ways to do kick counts:
You can do kick counts into your third trimester. If your provider is concerned about your babys movements, they may do other tests to check on your babys health.
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What Do The Results Mean
Down syndrome screening results can only show if you have a higher risk of having a baby with Down syndrome, but they can’t tell you for sure if your baby has Down syndrome You may have results that are not normal, but still deliver a healthy baby with no chromosomal defects or disorders.
If your Down syndrome screening results were not normal, you may choose to have one or more diagnostic tests.
It can help to speak to a genetic counselor before testing and/or after you get your results. A genetic counselor is a specially trained professional in genetics and genetic testing. He or she can help you understand what your results mean.
Learn more about laboratory tests, reference ranges, and understanding results.
C Ido Want To Have Prenatal Screening Now What
Once you have decided to proceed with prenatal screening, the next step is for you and your health care provider to choose which testing option is right for you. The following two tables compare available screening tests. Some factors that affect which prenatal screening tests you can choose from are:
- Where you live
- Screening choices vary according to where you live. Your health care provider will discuss what is available.
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Second Trimester Maternal Serum Screening
Second trimester screening, sometimes called a maternal serum screen or triple test, is done between 14 and 18 weeks into the pregnancy. It is usually offered to women who missed the combined first trimester screening test, or if it was not available where they were living.
It involves a blood test to look for hormones that could indicate the baby has Down syndrome or a neural tube defect. There will usually be a cost, but you can claim some of it back from Medicare.
If your baby is at increased chance, you will be offered a diagnostic test, which is optional, to confirm whether or not the baby has Down syndrome.
In addition to the MSS test, most pregnant women have a morphology scan at 18 to 22 weeks into the pregnancy to check on the babys growth and to see how the pregnancy is progressing. This can sometimes show signs of Down syndrome.
What You Need To Know
- Genetic screening can help diagnose the potential for certain genetic disorders before birth.
- First trimester screening is a combination of fetal ultrasound and maternal blood testing. This screening process can help determine the risk of the fetus having certain birth defects.
- Second trimester prenatal screening may include several blood tests called multiple markers. These markers provide information about the risk of having a baby with certain genetic conditions or birth defects.
- You may have ultrasounds performed at different times in your pregnancy to check for fetal growth, estimate your due date and look for any structural abnormalities in the baby.
- Additional testing during pregnancy may include amniocentesis, chorionic villus sampling , fetal monitoring, glucose testing and Group B strep culture.
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When Should You Get Genetic Testing
Genetic testing is ideally done before you start trying to get pregnant, says Angela Trepanier, MS, CGC, co-director of the genetic counseling program at Wayne State University and president of the National Society of Genetic Counselors. “But because so many pregnancies are unplanned, many couples get screened early in pregnancy,” she says.
Getting screened before you try to get pregnant can give you reassurance or can help you make an informed game plan for pregnancy. If it turns out that you are both carriers, you can be prepared for and bone up on what it means to have a baby with the genetic condition. You can also choose to learn about certain prenatal tests to check whether your baby’s healthy, and consider other options like egg or sperm donation or adoption.
Getting tested once you become pregnant can help you and your doctor decide the right prenatal tests for your baby, and what to look for if you choose to have them. If you know that your baby’s at an increased risk for having cystic fibrosis or sickle cell disease, for instance, your doctor can look for those conditions specifically through either a CVS or amniocentesis.
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