Moms Should Know Everything about Pregnancy Genetic Testing
Your informative guide to understanding pregnancy genetic testing
Mar 19, 2019
What is Pregnancy Genetic Testing?
Over the next nine months, expect a lot of visits to the doctor, also expect that your doctor may recommend some tests. Prenatal checkups and testing are crucial to the health of your growing baby and yours. There are some tests that you need to take and others that are optional. The lot of them, thankfully, are quick and painless.
The first thing you need to do is talk to your doctor about scheduling the tests that really fit your needs. Again, some of these tests are routine and part of your prenatal checkup. But there are others that you can take only if your doctor thinks that they would be helpful in your particular situation and if you agree that you want to be tested.
What exactly is pregnancy genetic testing? They are a series of tests or assessments performed during your pregnancy and they can give you a closer look into you and your baby's health. The methods to perform these tests are varied: blood work, vaginal swabs, invasive genetic testing, ultrasounds.
Some tests will check your baby, to asses if he or she has any medical condition while he or she is in the womb. Others can check your baby's DNA for genetic diseases. There are tests that you can take before you get pregnant, to check you or your partner's genes to show the chances that your baby would have a genetic disorder.
There are two main types of pregnancy or prenatal genetic tests.
1. Prenatal Screening Tests
These type of tests can tell you the chances that your fetus has a genetic disorder like aneuploidy (a condition in which there are missing or extra chromosomes) and some other additional disorders.
2. Prenatal Diagnostic Tests
These tests can actually tell if your fetus has certain genetic disorders. They are done on cells from the fetus or from the placenta. The procedures for these tests are invasive, the cells are obtained via amniocentesis (they withdraw a small amount of amniotic fluid by inserting a very thin needle on your stomach using an ultrasound to guide the procedure) or by chorionic villus sampling (CVS) ( they take a sample of tissue from your placenta).
The prenatal screening genetic tests include two different types of tests.
1. Carrier screening
This type of test is done to the parents-to-be. It's done by taking a sample of blood or tissue swabbed from inside the cheek. The purpose of these tests is to find out if one of the parents carries a gene for certain inherited disorders. It can be performed before or during pregnancy.
The most common type of disorders are:
- Cystic Fibrosis - a progressive, genetic disease that will cause infection to the lungs and over time, it makes breathing very limited
- Fragile X Syndrome - a genetic condition that causes developmental problems like learning disabilities and cognitive impairment
- Sickle cell disease - a group of inherited red blood cells disorders
- Tay-Sachs disease - a rare inherited disorder that destroys nerve cells
- Spinal Muscular Atrophy - a genetic disease that affects part of the nervous system controlling voluntary muscle movement
2. Prenatal screening genetic tests
These tests can screen your fetus for aneuploidy, neural tube defects (which are defects of the brain and spine) and for some defects of the heart, abdomen and facial features. They're done by drawing your blood or by the findings in an ultrasound.
The Timeline for Pregnancy Genetic Testing
You could get testing very early on in your pregnancy, starting from your first trimester. This test will ensure you that all is good with your pregnancy and that both you and your baby are healthy. Some of these tests are part of your prenatal care and others are optional. You can take them only if the doctor recommends them and if you agree.
You can start with the Carrier Screening Test. After discussing this option with your partner and with the doctor, you may decide to evaluate the possibility that either of you may be the carrier of any hereditary disease. This is done by drawing blood from both of you.
Genetic testing in the first trimester
As part of your routine prenatal care, you'll have to have an ultrasound, which would be the first chance to see your baby while the doctor makes all the needed measurements to make sure everything is OK with your bump.
You'll also need to take a urine test, actually, your urine will be tested throughout your pregnancy because it's through it your doctor can be sure you're healthy and have an idea how your pregnancy is going.
A diagnostic blood test is also necessary so your doctor could asses your blood characteristics and find out if you have any medical conditions that could affect your baby's health and yours. This blood test looks for: A complete blood count, to tally up the numbers of different types of cells in your blood. Blood type to know your Rh factor. It also looks for Rubella, hepatitis B and C, STD's, HIV and Tuberculosis.
These screening tests are offered to all pregnant women, but they're optional, you take them only if you agree. Doctors performed this genetic test between week 10 and 13, they're a mix of blood tests and ultrasound and they test your baby to see if he or she has a risk of Down Syndrome, trisomy 18 and spine and brain problems.
The screening includes:
- Maternal (serum) blood tests, to measure the level of a protein called PAPP-A and the level of a hormone called hCG, both of them are produced by your placenta.
- Ultrasound test for nuchal translucency, to look at the thickness of the gap the occurs in the back of the fetus's neck.
The results of these genetic screening test are analyzed taking into consideration your age and other relevant conditions.
As your baby starts to grow in size and weight, so will your belly.
Prenatal cell-free DNA screening
The cell-free DNA screening or non-invasive prenatal testing (NIPT) is a genetic test done after your 9 weeks of pregnancy. It's recommended to those women with a high risk of delivering a baby with a chromosome abnormality like Down Syndrome. As it happens, some of your baby's DNA winds up in your blood, so they take a sample and this sample gets analyzed by a lab.
The results are 99% accurate with this test to detect for Down Syndrome but remember that this is a screening test if you want a definitive answer you'll need a diagnostic test like a CVS or amniocentesis.
Chorionic villus sampling (CVS)
This is a genetic diagnostic test done by an invasive process where they perform a biopsy of the mother-to.be's placenta. It involves inserting a needle through the abdomen or a catheter through the cervix, that's how they get a sample. Since there's a small risk of miscarriage it's only performed on women who are at very high risk based on the results of the screening tests.
Genetic testing in second trimester
In this trimester, your doctor could offer this genetic testing. They're a chance to glean how your baby's doing so far.
Maternal serum quad test
The quad test is a multiple marker screening and it's the first part of your second-trimester genetic testing. You complement it with an ultrasound. It looks for certain proteins in your blood that, in abnormal levels, could indicate that your baby is at risk of being born with a chromosomal disorder.
The quad test measures levels of:
- a protein your baby makes named alpha-fetoprotein (AFP)
- your level of hCG
- a hormone from the placenta and baby's liver called estriol, and
- inhibin, another hormone from your placenta
If you didn't do the screen sequential in the first trimester, you have the option of taking the quad test between the 15 and 18 weeks of your pregnancy.
Ultrasound of Mid-pregnancy
This ultrasound is the complement of the quad test and is performed around week 20. You baby is checked for internal measurements and your doctor can confirm that the growth of your baby is OK for your due date. From this ultrasound, your doctor can assess the risk of your baby being born with a chromosomal disorder.
Depending on the results, you may want to confirm the diagnosis with a amniocentesis.
This is a diagnostic genetic test, it's invasive, it's performed between week 15 and 24 and it's very accurate (99%) in determining any chromosomal disorder in your unborn child. During the procedure, the doctor will insert a very long and thin needle through your abdomen and into the amniotic cavity to collect a small amount of fluid, This is sent to a lab to study the proteins and cells in the fluid.
This procedure also carries a small risk of miscarriage, so it's only performed on pregnant women who are at high risk based on age and the results of previous genetic screening tests.
Options and Costs for Pregnancy Genetic Testing
Genetic testing to look for chromosomal abnormalities or other problems with pregnancy, may not be covered by insurance plans, you'll have to check on your plan specifics to be sure. You may have to cover some of their costs.
The first-trimester screening tests costs will vary depending on your healthcare provider. According to Healthcare Bluebook (a company that offers information about medical pricing) will tell you that for an hCG test you could be charged $39 and for an ultrasound around $280. But in some cases, women have reported that they have been charged up to $600 for these screening tests.
Costs for genetic testing on your second trimester are varied too. You should check with your healthcare provider and insurance plan. For example, the cost for APF is $43 and for estriol is $63 (these two are part of the Quad Test).
The cost of CVS ranges between $1,300 to $4,800. Your health insurance plan may cover it if you have certain risk factors. You need to check that, otherwise, you'll have to cover the whole price.
An amniocentesis cost between $1000 to $7200.
Pregnancy Genetic Testing for Gender
The most common way to find out your baby's gender is through an ultrasound midway through your pregnancy (week 16-20). But there's a non-invasive genetic test that can be conducted in your 10th week of pregnancy that can be used to find out your baby's gender called Non-Invasive Prenatal Testing. This test is recommended for pregnant women who are at risk of carrying a baby with chromosomal abnormalities.
You can also find out your baby's gender with amniocentesis, but this is an invasive procedure that has a low risk of miscarriage, so if you're not at risk of carrying a baby with chromosomal abnormalities, maybe this is not the right test for you. Usually, an ultrasound is good enough to tell, unless your baby is keeping her/ his gender a secret with all the hide and seek!
Learning that you're pregnant could be the most joyous news of your life but it can turn one of the most anxious if you also learn that your baby could be at high risk of being born with some genetic disease or a chromosomal disorder. That is why getting all the information you can about pregnancy genetic testing is very important. With these tests, you can either rule out all your concerns or you can get prepared.
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