Preconception Carrier Screenings

If you are thinking about getting pregnant, there are many things to consider. One of these is whether you are at risk of passing a genetic condition on to your baby. Some genetic conditions require the gene to be passed down by both parents. Some only need the gene from one parent. If you know you are at risk, you may want to consider being tested. This kind of test is called a preconception carrier screening.

What is a preconception carrier screening?

Preconception carrier screening is a genetic test that can tell if you carry a gene for certain genetic disorders. It can tell you if you are at risk of having a child with a genetic disorder.

  • Preconception means the testing is done before you get pregnant.
  • Being a carrier means you have the gene inside your cells, but you don’t have the condition, or you have very mild symptoms. You could pass on the gene without knowing you have it.
  • screening is a test that is done to see if you have a condition even though you are not showing symptoms.

Path to improved health

Why is carrier screening done?

Some people know they have certain genetic conditions that run in their family. This means they could be a carrier of the gene. The testing will tell you if you have the gene. It can be part of your decision-making process when you are considering having a baby. Getting genetic testing done before getting pregnant gives you more options and more time to make decisions.

How is it done?

The testing is very simple. You provide a sample of your blood, saliva, or tissue inside your cheek. Tests can be done for specific genes or for many disorders. Types of tests include:

  • Targeted carrier screening – You are tested based on your family history or ethnic background. Some races or ethnicities are more likely to carry certain genes. For example, African-Americans are more likely to carry sickle cell disease. And Tay-Sachs disease is more common in certain groups, including people of French Canadian or Cajun descent.
  • Expanded carrier screening – A single sample is used to test for many disorders. Your race or ethnicity does not determine what you are screened for. These screenings tend to focus on severe conditions that start early in life.

Your doctor will discuss the different types of screenings with you and help you determine which is right for you. Your doctor may refer you to a certified genetics counselor or a genetic scientist who can explain the results in a way to help you make decisions.

What disorders are included in screenings?

Some expanded screening panels test for more than 100 different genetic disorders. Some of the most common disorders tested for include:

  • Cystic fibrosis.
  • Fragile X syndrome.
  • Sickle cell disease.
  • Tay-Sachs disease.
  • Huntington’s disease.
  • Spinal muscular atrophy.
  • Thalassemias and hemoglobinopathies (red blood cell disorders).

Things to consider

Most genetic disorders require each parent to pass down the gene. If only one partner tests positive for a certain gene, your baby should be fine. If both of you test positive, your baby has a 25% chance of developing the disorder. If this happens, you have several options. You can:

  • Get pregnant and undergo prenatal diagnostic testing to see if the fetus has the disorder.
  • Use in-vitro fertilization and test the fertilized egg before it is transferred into the uterus.
  • Use in-vitro with donor eggs or sperm from someone who does not carry the disorder.
  • Choose to not become pregnant.

These can be hard decisions to make. Talk to your doctor about the benefits and risks of each option. You can also talk to a genetic counselor. They are specialists who know more about genetic disorders and how they are inherited.

Questions to ask your doctor

  • Should I be screened for genetic disorders before I become pregnant?
  • What should I be screened for?
  • What kind of test will I have?
  • How long until I get the results of the tests?
  • What are the chances of the tests being wrong?
  • Does my partner need to be tested too?
  • Will I talk to a genetic counselor?
  • My partner and I both tested positive for a certain gene. Now what do we do?


March of Dimes: Your Checkup Before Pregnancy

National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development: What preconception tests do I need?