When to Get a Gene Test in Pregnancy—and What It Can Reveal About Your Baby’s Health

When you're pregnant, it's natural to wonder what’s going on inside your body—and more importantly, how your baby is doing. That’s where gene test in pregnancy comes in. These tests can help detect genetic abnormalities, chromosomal abnormalities, or birth defects early, often in the first trimester.

According to the CDC, about 1 in every 33 babies in the U.S. is born with a birth defect, which is why many parents consider prenatal genetic testing a helpful step—not just a medical formality.

In this article, we’ll walk you through when these tests are typically done, what they can uncover, and how to decide what’s right for you.

What Is a Genetic Testing in Pregnancy?

Genetic testing in pregnancy checks for genetic disorders and birth defects using a blood sample or ultrasound.

You may hear about first trimester screening tests like maternal serum screening or nuchal translucency screening, which look for chromosomal abnormalities early in pregnancy.

If results show higher risk, doctors may suggest diagnostic tests like chorionic villus sampling (CVS) or amniocentesis, which test amniotic fluid for neural tube defects or certain chromosome abnormalities.

According to ACOG, all pregnant women should be offered prenatal genetic screening tests, even without a family history.

A genetic counselor can help you decide what’s right.

What Can a Genetic Test Reveal About Your Baby’s Health?

Genetic testing in pregnancy provides valuable insights into your baby's health by identifying potential genetic conditions and birth defects. These tests, including prenatal screening tests and diagnostic tests, can detect various issues early in pregnancy, allowing for informed decision-making and preparation.

1. Genetic Abnormalities

Prenatal tests can uncover genetic abnormalities by analyzing fetal DNA through non-invasive prenatal testing (NIPT). This blood test examines cell-free DNA in the mother's bloodstream to assess the risk of conditions like Down syndrome.

• Detects chromosomal anomalies such as trisomy 21, trisomy 18, and trisomy 13.
• Provides early risk assessment without harming the fetus.
• Can be performed as early as 10 weeks of pregnancy.

2. Birth Defects

Prenatal screening helps identify birth defects like neural tube defects, which affect the spinal cord and brain. Maternal serum screening measures specific proteins in the mother's blood to assess the risk of these conditions.

• Screens for conditions such as spina bifida and anencephaly.
• Involves blood test measures like alpha-fetoprotein (AFP).
• Typically conducted during the second trimester.

3. Down Syndrome and Other Chromosomal Disorders

First trimester screening tests, combining nuchal translucency screening and maternal serum screening, evaluate the risk of Down syndrome and other chromosomal disorders. An increased measurement of the fetus's neck thickness may indicate a higher risk.

• Assesses risk for Down syndrome, trisomy 18, and trisomy 13.
• Combines ultrasound and blood sample analysis.
• Performed between 11 and 14 weeks of pregnancy.

4. Inherited Conditions from Carrier Parents

Carrier screening identifies if parents carry genes for certain genetic disorders like cystic fibrosis or sickle cell disease. If both parents are carriers, there's a higher chance the baby may inherit the condition.

• Involves a simple blood test.
• Can be done before or during pregnancy.
• Helps in planning and managing potential health issues.

5. Sex-Linked Genetic Conditions

Some disorders are linked to the X or Y chromosomes, affecting one sex more than the other. Prenatal diagnostic testing can detect conditions like hemophilia or Duchenne muscular dystrophy.

• Identifies risks for sex-linked genetic conditions.
• May involve chorionic villus sampling (CVS) or amniocentesis.
• Provides information for early intervention and management.

6. Risk of Passing on Rare Disorders

Advanced testing methods can assess the risk of rare genetic conditions by analyzing the genetic material of the fetus. This is especially important if there's a family history of such disorders.

• Detects rare conditions like Tay-Sachs disease.
• Involves detailed analysis of the fetus's DNA.
• Allows for early decision-making and care planning.

Understanding these aspects of genetic testing empowers you to make informed choices about your pregnancy and your baby's health. Consult with your healthcare provider or a genetic counselor to discuss the best options for your situation.

When Should You Get a Gene Test in Early Pregnancy?

Deciding when to undergo a gene test in early pregnancy is crucial for understanding your baby's health. These tests can identify potential genetic conditions, allowing for informed decisions and early interventions.

🕒 Optimal Timing for Genetic Testing

Early pregnancy offers several windows for genetic testing:

• First Trimester (10–13 weeks):
  • Chorionic Villus Sampling (CVS): Detects chromosomal abnormalities like Down syndrome.
  • Cell-Free DNA Testing: Screens for specific genetic disorders using maternal blood.
• Second Trimester (15–20 weeks):
  • Amniocentesis: Analyzes amniotic fluid to detect neural tube defects and other conditions.

According to the American College of Obstetricians and Gynecologists (ACOG), these tests are typically offered based on individual risk factors and should be discussed with your healthcare provider.

Importance of Early Testing

Early genetic testing can:

• Identify potential genetic disorders.
• Provide peace of mind or prepare for necessary interventions.
• Allow for early decision-making regarding the pregnancy.

It's essential to consult with your healthcare provider to determine which tests are appropriate for you and to understand the implications of the results.

Remember, while these tests provide valuable information, they also come with considerations that should be thoroughly discussed with a medical professional.

What Are the Types of Prenatal Genetic Tests?

1. Cell-free DNA (cfDNA) Testing

• A routine test done in early pregnancy using a maternal blood sample.
• Screens for chromosome abnormalities like trisomy 21 using fragments of fetal DNA.
• Especially helpful for identifying structural abnormalities early on.

2. Carrier Screening

• Checks if parents carry genes linked to certain birth defects or genetic conditions.
• Recommended when there’s a family history of inherited diseases.
• Often included as part of routine prenatal care or expanded panels.

3. Chorionic Villus Sampling (CVS)

• A prenatal diagnostic testing method done between 10–13 weeks of pregnancy.
• Involves collecting a small sample of placental tissue.
• May not detect open neural tube defects.

4. Amniocentesis

• Performed in the second trimester using a needle to extract amniotic fluid.
• Helps identify fetal abnormalities and spina bifida.
• Can detect issues with the abdominal wall or spinal cord.

5. Combined First Trimester Screening

• Includes fetal nuchal translucency and maternal serum screening.
• Measures fluid behind the fetus's neck and hormone levels to assess increased risk.
• Elevated results may lead to further testing.

6. Expanded Genetic Panels

• Tests a broader set of genetic material, including rare disorders.
• May require percutaneous umbilical blood sampling in special cases.
• Should be discussed with your healthcare provider during prenatal care planning.

How Do You Choose the Right Tests for Your Pregnancy?

Choosing the right prenatal test depends on your health, timing, and comfort level. Every pregnancy is different, so what’s right for one woman may not be for another. That’s why it’s important to ask questions—and get clear answers.

💬 Talk to Your Healthcare Provider

• Share your family history of genetic conditions or birth defects.
• Discuss your age, health conditions, and any previous pregnancy concerns.
• Ask if routine prenatal care already includes certain screening tests.

🧪 Know the Difference

• Screening tests (like cfDNA or maternal serum screening) tell you about risk.
• Diagnostic tests (like CVS or amniocentesis) give clearer answers—but they’re invasive tests.
• Some tests, like carrier screening, only need to be done once in a lifetime.

📅 Consider the Timing

• First trimester options are usually less invasive and give you more time to plan.
• Second trimester tests may look deeper into issues like open neural tube defects or structural abnormalities.

Remember, you’re not alone in making this decision. According to ACOG, discussing testing options with a genetic counselor is one of the best ways to understand what’s useful, what’s optional, and what feels right for you.

How Accurate Are These Diagnostic Tests?

Diagnostic tests like amniocentesis and chorionic villus sampling are highly accurate—often over 99% for detecting chromosomal abnormalities. But they’re not the first step for everyone. Most women start with screening tests, which only show risk.

If your screening test results come back abnormal, it doesn’t mean your baby definitely has a condition. It just means there’s a chance, and follow-up testing is offered.

While diagnostic tests carry a small risk due to their invasive nature, they give clearer answers. That’s why many pregnant women choose them only when it truly matters for decision-making or peace of mind.

Are There Any Risks with Gene Testing in Pregnancy?

Gene testing can give you peace of mind—or raise new questions. It's important to know the potential risks before saying yes to any test. Here’s what you should be aware of:

1. Physical risks from invasive tests

• Tests like chorionic villus sampling (CVS) or amniocentesis involve collecting tissue or amniotic fluid with a needle.
• This comes with a small chance of infection, cramping, or even miscarriage.
• The risk is low (about 1 in 500 to 1,000 procedures), but it’s still worth discussing with your healthcare provider.

2. Emotional stress

• Waiting for test results can be tough, especially if they’re not clear.
• Even screening test results that suggest a higher risk may cause anxiety, even though many turn out to be false alarms.
• Talking to a genetic counselor before and after testing helps many pregnant women feel more prepared.

3. False positives or unclear results

• No test is perfect.
• Screening tests can show a possible problem even when the baby is healthy.
• This might lead to more testing or stress that wasn’t needed.

4. Ethical dilemmas

• What would you do if a serious condition was confirmed?
• Some families face difficult choices they hadn’t expected.
• Having space to process these situations without pressure is crucial.

5. Privacy concerns

• Your genetic data and fetal DNA details are sensitive.
• Make sure your clinic follows strict privacy practices.
• You can ask how long your data is stored and who has access.

Being informed helps you feel more in control. The right test isn’t just about science—it’s about what feels right for you.

What Does Dr. Anshu Agarwal Say About Gene Testing in Pregnancy?

1. Early testing gives you clarity and time to plan

Dr. Anshu emphasizes that early gene tests during the first trimester—like cell-free DNA or carrier screening—can offer vital insights without putting the pregnancy at risk.

2. Not every woman needs every test

She recommends a personalized approach based on age, medical history, and family background instead of a one-size-fits-all method.

3. Emotional support is just as important as medical accuracy

Dr. Anshu advises couples to talk openly with their OB-GYN about test results, and seek counseling when needed—especially if results are complex or uncertain.

4. Focus on informed decisions, not fear

Her core message: gene tests are tools for informed, confident decision-making, not panic. The goal is to support the health of both mother and baby.

FAQs

1. Can you terminate a pregnancy based on genetic testing results?
Yes, but it depends on local laws and the gestational age. If a serious condition is confirmed through diagnostic testing, some parents may choose to terminate after medical counseling.

2. Should you do genetic testing before getting pregnant?
Pre-pregnancy carrier screening helps you understand if you or your partner carry genes for inherited disorders like cystic fibrosis. It’s optional but useful for planning.

3. What is the difference between genetic screening and diagnostic testing?
Screening tests estimate the risk of a condition—they don’t give a diagnosis. Diagnostic tests like amniocentesis or CVS confirm if a condition is actually present.

4. What is a chromosome test for a baby during pregnancy?
A chromosome test looks for conditions like Down syndrome or trisomy 18. It can be done through cell-free DNA testing, CVS, or amniocentesis.

5. How early can you detect chromosomal abnormalities in pregnancy?
As early as 10 weeks through non-invasive prenatal testing (NIPT). Earlier options like first trimester screening can also help flag risks for further testing.

Conclusion

Choosing whether or not to do a gene test in pregnancy is a personal decision—there’s no one-size-fits-all. The good news is, you don’t have to figure it out alone. From screening tests that measure things like human chorionic gonadotropin to diagnostic procedures that give clearer answers, your options are there to guide—not pressure—you.

Talk to your doctor, ask questions, and take your time. What matters most is that you feel confident, informed, and supported at every step. Your pregnancy journey is yours, and understanding your baby’s health is just one part of that bigger, meaningful story.