One of the conversations that comes up early in many pregnancies after 35 is prenatal genetic testing. The options have expanded considerably over the past decade, and for many women, navigating the different types of tests—what they look for, what their results mean, and how to make decisions that align with personal values—can feel overwhelming.
This article aims to provide a clear, evidence-based overview of the main prenatal genetic testing options available to women pregnant after 35. It is not a substitute for individualized guidance from your OB/GYN or maternal-fetal medicine (MFM) specialist, who can help you understand which tests are appropriate given your specific circumstances, health history, and preferences.
Most pregnancies after 35 result in healthy babies. Genetic testing is a tool for information, not a predictor of outcome—and deciding whether to undergo testing, and how to approach the results, is a deeply personal decision that only you can make, ideally with the support of your healthcare team.
Why Genetic Testing Is Often Discussed After 35
The association between maternal age and the likelihood of certain chromosomal conditions—most notably Down syndrome (trisomy 21)—has been documented in medical literature for decades. According to the American College of Obstetricians and Gynecologists (ACOG), the likelihood of a chromosomal condition at the time of prenatal testing increases gradually with maternal age, though it remains less than 1% for most women in their mid-30s and increases more substantially in the mid-to-late 40s.
It’s worth emphasizing that these are population-level statistics, not individual predictions. The majority of pregnancies—including those in women over 40—do not involve chromosomal conditions. At the same time, understanding the available screening and diagnostic tools allows you to make informed choices about your prenatal care.
Screening Tests vs. Diagnostic Tests
Prenatal genetic testing falls into two broad categories: screening tests and diagnostic tests. Understanding the difference is foundational to making sense of results and next steps.
Screening Tests
Screening tests assess the statistical likelihood that a pregnancy may be affected by certain chromosomal conditions or birth defects. They do not provide a definitive diagnosis. Positive or high-risk screening results indicate that further diagnostic testing may be worth considering—they do not confirm that a condition is present. Screening tests carry no procedural risk to the pregnancy and include blood tests and ultrasound assessments.
Diagnostic Tests
Diagnostic tests—chorionic villus sampling (CVS) and amniocentesis—analyze fetal chromosomes directly and can provide a definitive answer about whether a chromosomal condition is present. They involve a small procedural risk, which your provider can explain in detail. Diagnostic tests may be offered based on screening results, prior pregnancy history, or personal preference. As discussed in our article on pregnancy after 35: what to expect, many women choose not to pursue diagnostic testing even after a high-risk screening result—and that is a valid choice.
Non-Invasive Prenatal Testing (NIPT)
NIPT, also known as cell-free DNA screening, has become increasingly common since its introduction in the early 2010s. This blood test analyzes fragments of fetal DNA that circulate in the maternal bloodstream and can screen for chromosomal conditions including trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome), as well as sex chromosome differences.
NIPT generally has high sensitivity and specificity compared to earlier screening methods, though false positives and false negatives can and do occur. A positive NIPT result is not a diagnosis—confirmatory diagnostic testing via CVS or amniocentesis is typically recommended before clinical decisions are made. ACOG guidance indicates that NIPT may be offered to any pregnant woman, regardless of age or risk level, as part of informed prenatal care discussions.
First Trimester Combined Screening
First trimester combined screening typically takes place between 11 and 13 weeks of pregnancy and combines a blood test measuring pregnancy-associated plasma protein A (PAPP-A) and human chorionic gonadotropin (hCG) with a nuchal translucency (NT) ultrasound measurement. The NT measures the fluid at the back of the baby’s neck, as increased fluid can be associated with certain chromosomal conditions.
When these components are combined with maternal age and other factors, first trimester screening can identify pregnancies with increased likelihood of certain chromosomal conditions. Detection rates vary and the test has limitations, which your provider will explain. This screening does not affect the pregnancy and is a common component of first trimester prenatal care.
Second Trimester Screening and Anatomy Ultrasound
The second trimester quad screen (or triple screen) measures four markers in the maternal blood to assess the likelihood of chromosomal conditions and neural tube defects. It is typically performed between 15 and 20 weeks. Results are most meaningful when interpreted alongside first trimester results (a combined sequential approach).
The anatomy ultrasound, typically performed around 18 to 20 weeks, provides detailed imaging of fetal anatomy. While not a chromosomal screening test per se, it can identify structural findings that may prompt further evaluation. For women over 35, a detailed anatomy scan performed by a maternal-fetal medicine specialist is sometimes offered. Learn more about second trimester prenatal care milestones in our article on prenatal care milestones after 35.
Making Decisions That Reflect Your Values
One of the most important things to know about prenatal genetic testing is that there is no single right approach. Whether to undergo screening, whether to pursue diagnostic testing after a high-risk result, and what decisions might follow any given result are entirely personal—shaped by individual values, circumstances, beliefs, and support systems.
Some women find that testing provides reassurance or helps them prepare; others prefer not to have information they wouldn’t act on. Genetic counselors are trained professionals who can help you think through these decisions in a non-directive, supportive way. Requesting a referral to a genetic counselor—whether before, during, or after testing—is something many patients find valuable, and your OB/GYN can facilitate this.
Frequently Asked Questions
Is prenatal genetic testing required for women over 35?
No. Prenatal genetic testing is a personal choice, not a requirement. ACOG recommends that all pregnant women be offered information about available screening and diagnostic options, but the decision to undergo testing or not belongs to you. Your healthcare provider’s role is to ensure you have accurate information to make the choice that’s right for you.
What does a high-risk screening result mean?
A high-risk or positive screening result means the statistical likelihood of a chromosomal condition is higher than a defined threshold—it does not mean a condition is present. Many high-risk screening results are ultimately not confirmed by diagnostic testing. A genetic counselor or MFM specialist can help you understand what a specific result means and what, if any, next steps make sense for your situation.
Is NIPT the most accurate prenatal screening available?
NIPT generally has higher sensitivity and specificity than traditional first or second trimester screening for the conditions it tests, but it is still a screening test and not a diagnosis. Its performance can also be affected by factors such as low fetal fraction (the proportion of fetal DNA in the sample). No screening test is 100% accurate, and diagnostic testing remains the definitive route for a chromosomal diagnosis.
When should I discuss testing options with my provider?
Ideally, this conversation begins early in your first trimester, as some testing windows are time-sensitive. If you haven’t yet discussed prenatal genetic testing options with your OB/GYN or midwife, bringing it up at your next appointment is a good step.
Key Takeaways
- Prenatal genetic testing options include screening tests (like NIPT and first trimester combined screening) and diagnostic tests (like amniocentesis and CVS), which serve different purposes and carry different implications.
- Most pregnancies after 35 do not involve chromosomal conditions; age is one factor that influences statistical likelihood, not a deterministic predictor.
- A high-risk screening result is not a diagnosis—it indicates that further evaluation may be worth considering, and a genetic counselor can provide valuable support in understanding what results mean.
- The decision to undergo prenatal testing—and how to approach results—is deeply personal and should be made in consultation with your healthcare provider and, if helpful, a genetic counselor.
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.