One of the topics that comes up early in many pregnancies after 35 is prenatal genetic testing. The availability of testing options has expanded considerably in recent years, and many women find themselves navigating a range of choices — from non-invasive screenings to diagnostic procedures — that can feel both reassuring and complex.
Understanding the difference between screening tests and diagnostic tests, what information each can and cannot provide, and how to think about these options in the context of your individual values and circumstances is an important part of prenatal care. This overview offers evidence-based context to support those conversations with your healthcare provider.
Why Genetic Testing Is Often Discussed After 35
The likelihood of certain chromosomal variations in a pregnancy increases with maternal age. According to the American College of Obstetricians and Gynecologists (ACOG), this increase is gradual and continuous rather than a sharp threshold at any single age. Trisomy 21 (Down syndrome) is the most commonly discussed example, though other chromosomal variations also become somewhat more common with age.
ACOG recommends that all pregnant women, regardless of age, be offered information about prenatal genetic testing options. The decision about whether to pursue testing — and which tests — is a personal one that depends on individual values, what a person would do with the information, and various practical and medical factors. Most pregnancies after 35 result in healthy babies, and testing provides information, not a predetermined outcome.
Screening Tests: What They Can and Cannot Tell You
Prenatal screening tests assess the statistical probability that a pregnancy may be affected by certain chromosomal conditions. They do not provide a definitive diagnosis.
Cell-Free DNA (cfDNA) Screening / NIPT
Non-invasive prenatal testing (NIPT) analyzes fragments of fetal DNA circulating in the maternal bloodstream. It is typically available from around 10 weeks of pregnancy. Research suggests NIPT has high sensitivity and specificity for trisomies 21, 18, and 13, and may also screen for sex chromosome variations and, in some versions, microdeletions. However, NIPT is a screening test, not a diagnostic test — a positive result indicates increased risk and warrants diagnostic follow-up, while a negative result is reassuring but not a guarantee.
First Trimester Combined Screening
This approach combines an ultrasound measurement of the nuchal translucency (fluid at the back of the baby’s neck) with blood tests for certain pregnancy hormones, typically performed between 11 and 14 weeks. Results are expressed as a statistical risk ratio rather than a yes/no answer. For those also navigating the emotional dimensions of pregnancy after 35, understanding how to manage anxiety during pregnancy may be a helpful companion resource.
Second Trimester Serum Screening
Often called the quad screen, this blood test measures four markers in the second trimester to assess risk for chromosomal conditions and neural tube defects. It can be used alone or as part of an integrated screening approach in combination with first trimester testing.
Diagnostic Tests: Definitive Chromosomal Information
Unlike screening tests, diagnostic procedures provide definitive information about a baby’s chromosomal makeup. They carry a small risk of pregnancy loss and are therefore typically offered to those with elevated screening results, a family history of certain genetic conditions, or other clinical indications.
Chorionic Villus Sampling (CVS)
CVS involves sampling a small amount of placental tissue, typically between 10 and 13 weeks of pregnancy. It provides chromosomal information in the first trimester, which some people value for earlier decision-making. The procedure-related pregnancy loss risk is generally cited as less than 1% in experienced centers, though this varies.
Amniocentesis
Amniocentesis involves sampling a small amount of amniotic fluid, typically performed between 15 and 20 weeks. It is generally considered highly accurate for chromosomal diagnoses and can also test for specific genetic conditions if indicated. The procedure-related risk is similar to CVS in experienced settings.
Making Decisions About Testing
There is no universally right answer about whether to pursue prenatal genetic testing, or which tests to choose. Factors that some people weigh include what they would do with the information, whether earlier versus later information matters to them, their anxiety levels regarding testing and waiting for results, and how they weigh the small procedural risks of diagnostic testing against the value of definitive information.
A genetic counselor can be an invaluable resource in this process. Genetic counselors specialize in helping individuals and families understand genetic information and navigate testing decisions in the context of their own values and circumstances. Many are available through maternal-fetal medicine practices or can be accessed through referral from an OB/GYN. Understanding prenatal care considerations after 35 more broadly may also help frame these decisions.
Frequently Asked Questions
Is genetic testing required during pregnancy after 35?
No. ACOG recommends that all pregnant women be offered information about testing options, but testing is not mandatory. The decision to pursue testing — and which tests — is entirely personal and should be made based on your own values, preferences, and medical circumstances in consultation with your healthcare provider.
What happens if a screening test comes back positive?
A positive result on a screening test means that the statistical risk for a particular chromosomal condition is elevated, not that the baby definitely has that condition. A genetic counselor and maternal-fetal medicine specialist can help interpret results, explain options, and support you through the process. Many positive screens are followed by diagnostic testing to provide clearer information.
How accurate is NIPT?
NIPT has relatively high sensitivity and specificity for the conditions it screens for, particularly trisomies 21, 18, and 13. However, factors such as placental mosaicism, a low fetal fraction, and other technical considerations can affect results. False positives and false negatives, while uncommon, do occur. A genetic counselor can help interpret results in the context of individual circumstances.
At what point in pregnancy should I discuss testing options?
Ideally, these conversations happen in early pregnancy or even preconception, since some testing options (like CVS and NIPT) are available in the first trimester and timing matters for access. Raising the topic at your first prenatal appointment gives the most options. If you’re already in the second trimester, some options are still available.
Key Takeaways
- Prenatal genetic testing options include non-invasive screenings (like NIPT) and diagnostic procedures (like CVS and amniocentesis), which provide different types of information.
- Screening tests assess statistical risk; diagnostic tests provide definitive chromosomal information but carry a small procedural risk.
- The decision to pursue testing is personal and should be made in consultation with a healthcare provider or genetic counselor based on individual values.
- ACOG recommends that all pregnant women be offered information about testing options regardless of age, and most pregnancies after 35 result in healthy babies.
- A genetic counselor can be an especially helpful resource for navigating 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.