Should You Screen Your Genes Before You Conceive?

New tests, including at-home kits, now make it easier than ever to check your odds of a having a baby with a genetic disorder before you get pregnant.

Doctors usually recommend genetic testing if you or your partner has a higher risk of passing on certain diseases, like cystic fibrosis. And because of these screening tests, the number of people who have some disorders, like Tay-Sachs disease, has gone way down.

But what if you're not at high risk? Should you check your genes before you get pregnant? Your doctor or a genetic counselor can help you decide.

How Genetic Tests Work

Many genetic disorders happen when someone has two bad copies of a gene, one from each parent. If you have only one faulty copy, you won't have symptoms of the condition, but you are a "carrier" for it. Your baby will be born with the disorder only if both you and your partner pass the bad gene to him.

To test if you're a carrier of a genetic disease, your doctor takes a small sample of your saliva or blood during a checkup before you get pregnant. She'll send the samples to a lab for testing. If you use an at-home kit, you'll take the sample and send it to a lab yourself.

The tests look closely at your DNA for genes that are linked to certain diseases. Standard screening tests check for:

  • Cystic fibrosis
  • Fragile X syndrome
  • Blood disorders such as sickle cell disease
  • Tay-Sachs disease
  • Spinal muscular atrophy

Newer tests, called expanded genetic carrier screenings, can also find flawed genes for more than 400 other disorders, some of which are rare and have few treatments.

Who Needs Screening?

If you or your partner has a genetic disorder that runs in the family, your doctor will probably recommend that you both get a genetic test. She may also suggest testing if you belong to an ethnic group with a high risk of certain genetic diseases, such as:

  • Ashkenazi Jewish (Tay-Sachs disease and others)
  • African-American (sickle cell disease)
  • Mediterranean and Southeast Asian (thalassemia)

If you're not in one of these groups, think about what the results of a screening might mean for you before you decide to get one.

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Pros and Cons of Genetic Testing

A test before you're pregnant can't tell you without a doubt whether your child will have a disorder. Results from a genetic screening test only help doctors more accurately predict your chances of passing problem genes to your children.

Some of the advantages of genetic testing are:

Finds unknown problems. Many of the flawed genes these tests find aren't linked to your race, ethnicity, or family history. You might never know you or your partner carries them. If you know your risk, you can make informed decisions about your family.

Provides answers about your family history. The results can help you figure out if you're in a high-risk group, especially if you don't know your family history or if you come from a multiethnic background.

The test is easy. Taking a blood or saliva sample before you're pregnant is quick and harmless.

Some disadvantages:

Results may be incorrect. No test is 100% accurate. Yours could say you aren't a carrier for a gene when you really are. On the flip side, very rarely, a result could say you carry a faulty gene when you don't. These incorrect results, or the possibility that your tests might be wrong, can be stressful when you're making decisions about having a baby.

You can't always know how the genes will affect your baby. Even if you know there's a chance your child will inherit flawed genes, you may not be able to tell if she'll show symptoms of the disorder, how severe they'll be, or if they'll get worse over time, depending on the disease.

What Else to Consider

Genetic carrier tests can give people important information, but they're not right for everyone. Think things through before you make your decision:

How might the results affect me? Will knowing your chances of passing down a genetic disorder make you more or less worried during pregnancy?

How might the results affect my family? Sharing (or not sharing) your results with family members who may also be affected by the information could cause tension.

What will my next steps be? Think ahead about how you might handle news of your results. It may help to talk with a genetics counselor, who can help you think about the possibilities and your options. Ask your doctor for a recommendation.

WebMD Medical Reference Reviewed by Traci C. Johnson, MD on February 14, 2018

Sources

SOURCES:

University of California at San Francisco Medical Center: "Preconception Carrier Screening and Testing for Genetic Disorders."

The American College of Obstetricians and Gynecologists: "Preconception Carrier Screening," "Expanded Carrier Screening in Reproductive Medicine -- Points to Consider."

Cystic Fibrosis Foundation: "Introduction to Cystic Fibrosis."

Edwards, J. Obstetrics and Gynecology, 2015.

Shapira, S. Maternal and Child Health Journal, 2006.

Genetics Home Reference: "Genetic Testing."

Penn Medicine: "Preimplantation Genetic Diagnosis (Embryo Screening)."

© 2018 WebMD, LLC. All rights reserved.

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