One of the topics that often comes up early in conversations about pregnancy after 35 is prenatal genetic testing. If you’re pregnant or planning a pregnancy, your OB/GYN or midwife has likely mentioned these options—or you may have heard the term “advanced maternal age” in the context of testing recommendations. Understanding what these tests are, what they can detect, and what they can’t is an important part of navigating prenatal care.
It’s worth starting with reassurance: the vast majority of pregnancies after 35 are healthy, and most babies are born without chromosomal conditions. That said, the statistical risk of certain chromosomal variations does increase with maternal age, which is why genetic testing options are typically discussed more thoroughly for women in this age group. The decision about whether to pursue testing is deeply personal and should be made in conversation with your healthcare team.
This overview outlines the main types of prenatal genetic testing, what they’re designed to detect, and how to think about the decision-making process.
What Research Shows About Age and Chromosomal Risk
According to the American College of Obstetricians and Gynecologists (ACOG), the risk of chromosomal abnormalities—including Down syndrome (trisomy 21), trisomy 18, and trisomy 13—does increase with maternal age. For example, the risk of Down syndrome at age 35 is approximately 1 in 350, compared to roughly 1 in 1,200 at age 25. By age 40, the risk increases further to approximately 1 in 100.
These statistics reflect population-level risk, not individual certainty. Many women over 35 and 40 have babies without chromosomal conditions, and the numbers above represent the additional context that informs why testing conversations are more routine for this age group.
Screening Tests vs. Diagnostic Tests
A key distinction in prenatal genetic testing is between screening tests and diagnostic tests. Understanding the difference helps clarify what results actually mean.
Screening Tests
Screening tests estimate the statistical probability that a pregnancy is affected by a chromosomal condition. They are non-invasive and carry no risk of pregnancy loss. A “positive” or “high-risk” screening result does not mean a baby definitely has a condition—it means further evaluation may be warranted. Common screening tests include:
- Cell-free DNA (cfDNA) screening / Non-invasive prenatal testing (NIPT): A blood test that analyzes fetal DNA in the mother’s bloodstream. It screens for Down syndrome, trisomies 18 and 13, and sex chromosome conditions with relatively high sensitivity and specificity, though it is still a screening test, not a diagnostic one.
- First-trimester combined screening: Combines a nuchal translucency ultrasound (measuring fluid at the back of the baby’s neck) with blood tests measuring PAPP-A and hCG levels.
- Second-trimester quad screen: A blood test measuring four markers associated with chromosomal conditions and neural tube defects.
Diagnostic Tests
Diagnostic tests—amniocentesis and chorionic villus sampling (CVS)—can confirm or rule out chromosomal conditions with high accuracy. Unlike screening tests, they provide a definitive chromosomal result. However, both carry a small risk of pregnancy loss (generally cited at around 0.1–0.5% depending on the procedure and provider), which is an important factor in the decision-making process.
Diagnostic testing is typically offered following a positive or high-risk screening result, or in situations where there are other clinical concerns. For more context on navigating prenatal care decisions after 35, our broader guide covers the range of considerations involved.
Making the Decision About Testing
ACOG recommends that all pregnant women, regardless of age, be offered information about both screening and diagnostic testing options. The decision about whether to pursue testing—and which type—is personal and depends on a range of factors:
- What information would be helpful or meaningful to you
- How you and your partner would respond to different types of results
- Your comfort level with the small risks associated with diagnostic procedures
- Your values, beliefs, and reproductive goals
There is no universally “right” answer. Some women choose comprehensive testing because the information helps them prepare; others prefer to forgo certain tests because uncertainty is more manageable than potential anxiety from results. Both approaches are valid.
Questions to Discuss With Your Provider
When meeting with your OB/GYN or midwife, some questions that may be helpful to explore include:
- What tests are available at my gestational age, and what does each detect?
- What would a positive screening result mean in practical terms?
- What would I do with the information from a diagnostic test?
- Are there any factors in my health history that affect my risk profile?
What Testing Cannot Tell You
Prenatal genetic testing provides information about chromosomal conditions, but it doesn’t screen for all possible conditions or birth differences. The majority of birth differences are not chromosomal in origin, and standard genetic testing does not detect them. This is worth bearing in mind both when considering testing and when interpreting results.
A normal NIPT or amniocentesis result is reassuring about the conditions it tests for, but it’s not a guarantee of an uncomplicated pregnancy or a baby born without any health challenges. Your healthcare provider can explain the scope of each test clearly.
Emotional Aspects of Genetic Testing
For many women, the decision about genetic testing—and waiting for results—can be emotionally significant. It’s not uncommon to feel anxious during the waiting period, or to grapple with complex feelings about what various results might mean. If you’re finding the process stressful, talking with your OB/GYN, a genetic counselor, or a therapist can provide valuable support. Exploring strategies for managing pregnancy anxiety may also be helpful during this time.
Frequently Asked Questions
Is genetic testing mandatory during pregnancy after 35?
No. All prenatal genetic testing is optional. ACOG recommends that all pregnant women be offered information about available tests, but the decision to pursue testing is yours. Your provider can help you understand the options so you can make a choice that aligns with your values and circumstances.
What is the difference between NIPT and amniocentesis?
NIPT is a non-invasive blood screening test that estimates the probability of certain chromosomal conditions—it is not diagnostic. Amniocentesis is a diagnostic procedure involving a sample of amniotic fluid that can confirm or rule out chromosomal conditions with high accuracy, but carries a small risk of pregnancy loss. Your provider can explain which is appropriate based on your situation.
When is the best time to discuss genetic testing with my doctor?
Many genetic tests have specific gestational age windows. First-trimester screening and CVS are typically offered between weeks 10–13; amniocentesis is generally performed around weeks 15–20. Ideally, genetic testing should be discussed early in the first trimester so you have time to make informed decisions within the appropriate timeframes.
Does a “high risk” screening result mean my baby has a chromosomal condition?
Not necessarily. A high-risk screening result means the probability of a chromosomal condition is statistically elevated compared to average—it is not a diagnosis. Many women with high-risk screening results go on to have healthy pregnancies. A diagnostic test (amniocentesis or CVS) is the appropriate next step to obtain a definitive answer.
Key Takeaways
- Prenatal genetic testing options include both non-invasive screening tests and diagnostic procedures; each provides different types of information
- The risk of chromosomal conditions increases with maternal age, which is why testing conversations are more routine after 35—though most pregnancies at this age are healthy
- NIPT and other screening tests estimate probability; only diagnostic tests (amniocentesis, CVS) can confirm or rule out a chromosomal condition
- The decision to pursue genetic testing is personal and should be made in conversation with your healthcare provider based on your values and circumstances
- Genetic counselors are an excellent resource for navigating complex testing decisions and interpreting results
Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Individual health situations vary significantly. Always consult a qualified healthcare provider before making decisions related to your health, fertility, or pregnancy.
About the Author
Emily Carter is a women’s health writer focused on fertility, pregnancy after 35, and sleep changes in midlife. She writes research-informed, non-alarmist content to help women navigate reproductive and hormonal transitions with clarity and confidence.