One of the aspects of pregnancy after 35 that most women encounter early in their prenatal care is a conversation about genetic testing. The range of available tests has expanded considerably in recent years, and the landscape can feel overwhelming — particularly when you’re also navigating the emotional complexity of an advanced maternal age pregnancy. Understanding what each type of test does and doesn’t tell you, and what role each might play in your prenatal care, can help you approach these decisions with more clarity.
It’s important to state clearly at the outset: prenatal genetic testing is a personal decision. There is no single “right” choice, and what makes sense for one woman — based on her values, her specific risk factors, her pregnancy history, and how she would use the information — may differ significantly from what makes sense for another. The goal of this overview is to inform, not to steer.
Your OB/GYN or midwife, and potentially a genetic counselor, are the most appropriate resources for helping you determine which tests, if any, are appropriate for your individual situation. Genetic counselors specialize in explaining testing options and helping patients understand what results may mean for them — they can be an invaluable resource if you’re navigating this topic.
Why Age Factors Into Genetic Testing Discussions
Research has consistently documented that the risk of certain chromosomal differences in pregnancies — most notably trisomy 21 (Down syndrome), as well as trisomy 18 and trisomy 13 — increases with maternal age. This is related to changes in egg quality and the mechanisms of chromosomal separation during egg development. The increase in risk is gradual and begins before age 35, but 35 has historically been used as a threshold in obstetric guidelines where testing discussions are more actively recommended.
According to the American College of Obstetricians and Gynecologists (ACOG), all pregnant women, regardless of age, should be offered prenatal screening and diagnostic testing options. Age 35 is no longer used as a strict cutoff for who “qualifies” for testing — rather, testing is discussed with all pregnant women, with the understanding that individual decisions will vary.
Screening Tests vs. Diagnostic Tests
A fundamental distinction in prenatal genetic testing is between screening tests and diagnostic tests. Understanding this difference is essential for interpreting what any result means.
Screening Tests
Screening tests assess the statistical likelihood of certain chromosomal differences being present. They do not diagnose. A “positive” or “high-risk” screening result means there is an elevated statistical probability of a particular condition — not a confirmation that the condition is present. Many pregnancies with high-risk screening results are ultimately chromosomally typical. Conversely, a “low-risk” result does not eliminate the possibility of a chromosomal difference — it indicates that the statistical likelihood is lower.
Diagnostic Tests
Diagnostic tests, primarily amniocentesis and chorionic villus sampling (CVS), can provide more definitive information about a pregnancy’s chromosomal makeup. These tests analyze fetal DNA or cells directly and can confirm or rule out specific chromosomal differences. They carry a small risk of pregnancy loss (though risks with modern techniques are quite low), which is an important factor in the decision-making process for many women.
Cell-Free DNA Screening (NIPT)
Non-invasive prenatal testing (NIPT), also called cell-free DNA screening, analyzes fragments of fetal DNA circulating in maternal blood. It has become widely used and is available starting around 10 weeks of pregnancy. NIPT can screen for the most common chromosomal differences (trisomies 21, 18, and 13, and sex chromosome conditions) with higher sensitivity and lower false positive rates than earlier screening methods.
NIPT is a screening test, not a diagnostic test — a positive NIPT result should be followed by confirmatory diagnostic testing before decisions are made based on it. Some insurance plans cover NIPT for women over 35 or with elevated risk factors; coverage varies. Your OB/GYN can advise on availability and how it fits into your prenatal care plan. Understanding your first trimester prenatal care after 35 in full can help you see where genetic testing fits within the broader picture.
First Trimester Combined Screening
First trimester combined screening integrates a nuchal translucency ultrasound (which measures fluid at the back of the fetal neck) with blood tests measuring two pregnancy hormones (PAPP-A and free beta-hCG). Combined with maternal age, these results generate a statistical risk estimate. This type of screening has been available longer than NIPT and remains an option in many clinical settings, though NIPT has largely supplanted or supplemented it in recent years.
Second Trimester Screening and Anatomy Ultrasound
The anatomy ultrasound, typically performed around 18-20 weeks, is an important component of prenatal care that provides detailed information about fetal development and anatomy. While it is not specifically a chromosomal screening test, it can identify structural findings that may prompt further evaluation.
The maternal serum “quad screen” (measuring four hormones in maternal blood) is a second trimester screening option that can be used alone or as part of an integrated screening approach. Understanding how second trimester screening fits into the overall picture is another topic worth discussing with your care team, particularly if first trimester screening revealed anything that warrants follow-up. Many women also find it helpful to understand what to expect at the 20-week anatomy scan as pregnancy progresses.
Frequently Asked Questions
Is genetic testing required during pregnancy after 35?
No — genetic testing is offered and recommended for discussion, but it is not required. The decision to test, which tests to pursue, and what to do with results are personal choices that vary based on individual values, circumstances, and how the information would be used. Many women choose comprehensive testing; others decline some or all screening. Both are valid choices, and your care team should support whichever direction you choose.
What does a positive NIPT result mean?
A positive (high-risk) NIPT result indicates an elevated statistical probability of a chromosomal difference — it does not confirm a diagnosis. False positives occur, and a positive NIPT result is generally followed by an offer of diagnostic testing (CVS or amniocentesis) to provide more definitive information. Working with a genetic counselor after receiving any positive screening result can help you understand what the result means and what options are available to you.
What is the risk of pregnancy loss from amniocentesis?
The risk of procedure-related pregnancy loss from amniocentesis performed at experienced centers is very low — current estimates suggest approximately 0.1-0.3%, though this varies by provider and setting. CVS carries a comparable or slightly higher risk depending on approach and operator experience. Your provider can give you information specific to their practice and experience. These risks are part of the decision-making calculus alongside the information the test would provide.
At what point in pregnancy should these testing decisions be made?
Different tests are available at different gestational windows. NIPT and first trimester combined screening are generally available starting around 10-12 weeks. CVS is typically performed between 10-13 weeks. Second trimester screening and amniocentesis are generally performed later, around 15-22 weeks. Because some testing windows close earlier in pregnancy, discussing testing options early in your prenatal care is advisable.
Key Takeaways
- The risk of certain chromosomal differences in pregnancies increases gradually with maternal age, which is why prenatal genetic testing discussions are a standard part of care after 35 — though testing is offered to all pregnant women regardless of age.
- Screening tests (including NIPT and first trimester combined screening) provide statistical risk estimates, not diagnoses — a high-risk result requires follow-up with diagnostic testing to confirm or rule out a finding.
- Diagnostic tests (CVS and amniocentesis) provide more definitive chromosomal information but carry a small risk of pregnancy loss that factors into the decision-making process.
- NIPT has become widely used for its higher sensitivity and lower false positive rates compared to earlier screening approaches, though it remains a screening tool, not a diagnostic one.
- Prenatal genetic testing decisions are deeply personal — working with your OB/GYN and potentially a genetic counselor can help you make choices that align with your values and circumstances.
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.