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Prenatal Care: When Should I Get Genetic Testing?

Published on 07/02/21

Our genetics influence a baby’s development. This could be the color of their hair or eyes, as well as the development of certain genetic disorders and birth defects. During pregnancy, women will be offered a variety of genetic screening tests during their first and second trimesters of pregnancy. This genetic testing is only to help evaluate the potential risks or problems in their unborn baby.

Genetic testing is done when women want to know if there are any risks before their baby is born. Most women prefer to know if there are any issues during pregnancy rather than after. This helps with planning and decisions before the time comes. Also, it allows them to gain more knowledge on any possible risks.

The ultrasound exam measures the thickness of the fetus’s neck. There is a higher risk that the fetus may have Down Syndrome or another type of aneuploidy if the measurement is abnormal. An abnormal measurement is also linked to:

  • Heart defects
  • Skeleton
  • Abdominal wall

Cell-Free DNA Testing

Cell-Free DNA Testing is where a tiny amount of DNA is released from the placenta into a pregnant woman’s bloodstream and sampled. This cell-free DNA test can help to look for:

  • Down Syndrome
  • Patau Syndrome
  • Edwards Syndrome
  • Problems with the sex chromosomes, micro-deletion syndromes, and fetal gender

This test happens starting around 10 weeks into the pregnancy and takes 7-10 business days to get results. If the cell-free DNA test comes back positive, there should be a follow-up diagnostic test with CVS or amniocentesis.

What Is Prenatal Genetic Testing?

Prenatal genetic testing gives information about the baby prior to delivery. Specifically, it gives information about certain genetic disorders the baby may have.

Genetic Disorders

Genetic disorders are detected by looking for changes in a person’s genes or chromosomes:

  • Trisomy: an extra chromosome
  • Aneuploidy: a condition where the baby may possibly have a missing or extra chromosome
  • Monosomy: a missing chromosome

Inherited Disorders are changes in the genes called mutations that could include Tay-Sachs disease, cystic fibrosis, or sickle cell disease.

There are many, many more. In most cases, however, both parents must carry the same gene to have an affected child.

Types Of Genetic Testing

There are a few types of prenatal genetic tests that we will cover:

Prenatal Screening Tests

This test can tell you the chances that your fetus has an aneuploidy and few other disorders.

Prenatal screening tests include tests like the carrier and prenatal genetic screening test.

Prenatal Genetic Screening

This test is done by blood. There also may be an additional ultrasound exam. This looks for defects in the fetus usually by the abdomen, in the facial features. It also looks for defects of the brain and/or spine called neural tube defects, as well as conditions related to aneuploidy. This includes DNA testing and an AFP blood test.

When there is an option for genetic screening, it’s imperative to consider how this information might affect a couple, especially the expecting mother. The results could come back abnormal and not all couples are ready for that conversation. 

However not all genetic screening occurs while a woman is pregnant. There are some specific cases where it may be done before pregnancy. I.e. Preconception genetic screening. These tests are considered carrier tests that can be done to determine whether either partner carries a specific gene for genetic disorders. Some which run in families. For example:

  • Cystic fibrosis
  • Sickle cell anemia

These can be passed on to the unborn child. 

Genetic screening is an option. So whether or not a mother decides to undergo testing is up to her but it can dredge up anxiety and conflicting emotions.

Prenatal Diagnostic Tests

These tests look for certain disorders in the baby. The tests are conducted on cells from the placenta or amniotic fluid. Obtained through chorionic villus sampling (CVS) or amniocentesis. Both of these tests are invasive procedures and come with a risk of a complication that can lead to a miscarriage. 

Some women may question why prenatal diagnosis is important because if the test comes back positive, it can’t be cured or treated. Most doctors would answer that knowing is better than a surprise. Knowing the results ahead of time can help parents prepare their lives for a baby who may or may not have special needs.

Carrier Screening

This test is done on couples who are considering having children. Doctors use a blood or saliva sample. This test is used to find whether a person carries a genetic variant associated with a genetic disease.

How Accurate Are Genetic Screening Tests?

As for all tests, there’s always a chance of a false-positive and false negative-result. Your doctor can give you more of an idea of which risks are associated with which tests. 

It is your choice to decide on prenatal testing. These tests are not required in prenatal care. They are helpful in the long run post-delivery. Also to note: a positive screening test isn’t definite, it only tells you that your baby is at a higher risk for an aneuploidy. Diagnostic tests are used to help understand more of a certain result. 

The knowledge these tests give parents helps them have time to become more knowledgeable about a concern or disorder and the medical care that may be needed. 

Some parents decide that they don’t want to know any of this before the child is born, which is quite alright as these tests are optional. There is no right or wrong answer.

The Risks of Genetic Screening Tests

During your early prenatal visits, your doctor will ask a lot of questions about you and your partner’s family health history. Everything from ethnic background, medical histories, ages, and family history can help pinpoint if there are any genetic diseases that might affect your child. If your doctor considers you at higher risk for inheriting a genetic disease, they may recommend specific genetic testing.

Some common genetic diseases for specific backgrounds include:

African Heritage: sickle cell anemia

Italian, Greek, Middle Eastern, Asian and African: thalassemia

Ashkenazi Jews: Tay-Sachs disease

Caucasian: cystic fibrosis

Some parents are not sure whether testing is right for them. If they are carriers for genetic diseases, they are not sure what to do with abnormal results, or what pregnancy options are available to them.

Testing is just information that can be helpful to you and your doctor about your baby’s birth. If your baby is found to have special needs, making arrangements ahead of time with certain specialists can be extremely helpful. This way the baby can be treated from the moment they’re born and leaves time for the parents to mentally prepare for any specific needs. 

It’s normal to have a lot of questions about preconception, pregnancy, and prenatal care. Talk to your healthcare provider about meeting you and your baby’s needs. The option is yours! There is no right or wrong answer. Each family does what they feel is right for them.

All in all, if you have any questions or concerns about genetic testing and risks to your baby, talk to the team at Rosh Maternal & Fetal Medicine. They can help you carefully consider all of your options and help you choose what’s right for you.

Considering Genetic Testing or Genetic Diagnostic Testing? Contact Rosh Maternal & Fetal Medicine in NYC

There’s nothing more important than prenatal care, the genetic health, and protection of you and your baby throughout your pregnancy.

The team at Rosh Maternal & Fetal Medicine provides medical checkups, screening tests, and emotional support as you go through pregnancy. Their doctors are also experts in high-risk pregnancies and genetic testing. If you have any questions about prenatal care, call their office in the Midtown East area of New York City, or schedule an appointment online.