One of the most significant aspects of prenatal care that distinguishes pregnancy after 35 is the recommendation for—and discussion about—genetic screening and diagnostic testing. For many women, these conversations begin even before pregnancy or shortly after a positive test, and navigating the options, their purposes, and their limitations can feel overwhelming without some background context.
This article provides an overview of the types of prenatal genetic testing commonly discussed for women 35 and older, what each is designed to detect, and what the limitations of each test are. It is intended as background information to support conversations with your healthcare provider, not as guidance for individual medical decisions.
Why Age 35 Is a Reference Point in Prenatal Care
The age of 35 has historically been used as a threshold in obstetric care for recommending certain types of prenatal testing, based on the relationship between maternal age and the risk of chromosomal conditions such as Down syndrome (trisomy 21). According to the American College of Obstetricians and Gynecologists (ACOG), research has established that the probability of chromosomal abnormalities in pregnancies increases with maternal age—a relationship associated with the age-related increase in chromosomal errors during egg development discussed in earlier sections.
ACOG now recommends that prenatal screening be offered to all pregnant women regardless of age, not just those 35 and older, reflecting the reality that chromosomal conditions can occur in pregnancies at any maternal age and that modern screening technologies have made testing accessible and informative across the age spectrum. However, older maternal age does increase the prior probability of certain findings, which influences how test results are interpreted.
The Difference Between Screening and Diagnostic Testing
This distinction is fundamental and often a source of confusion. Screening tests estimate the probability that a pregnancy is affected by a specific condition; they do not diagnose. A screening test result—whether low-risk or high-risk—is a probability statement, not a definitive answer. Diagnostic tests, by contrast, directly examine fetal chromosomes and can provide definitive answers, but they are more invasive and carry a small risk of pregnancy loss.
Screening Tests
Screening approaches commonly offered in pregnancy after 35 include cell-free DNA testing (also called non-invasive prenatal testing or NIPT), first-trimester combined screening, second-trimester serum screening (quad screen), and anatomy ultrasound. These tests vary in what they screen for, their timing in pregnancy, and their performance characteristics—including detection rates and false positive rates.
Diagnostic Tests
Diagnostic options include chorionic villus sampling (CVS), typically performed in the first trimester between 10-13 weeks, and amniocentesis, typically performed in the second trimester from about 15-20 weeks. Both involve taking a sample of tissue or fluid to directly analyze fetal chromosomes. Current research indicates that the risk of pregnancy loss associated with these procedures in experienced hands is low—approximately 0.1-0.3% for amniocentesis in high-volume centers—though this risk is not zero, and it is a factor women weigh when deciding whether to pursue diagnostic testing.
Cell-Free DNA (NIPT): What It Is and What It Measures
NIPT analyzes fragments of fetal DNA circulating in maternal blood and is typically offered from around 10 weeks of pregnancy. It screens for chromosomal conditions including trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), trisomy 13 (Patau syndrome), and sex chromosome abnormalities. Some panels also screen for certain microdeletion syndromes, though the evidence base for these additions is more limited.
NIPT has high sensitivity and specificity for the main trisomies, particularly in pregnancies where the underlying prevalence is higher—which is one reason it performs well in older maternal age groups. However, NIPT is still a screening test: a positive result requires confirmation through diagnostic testing before clinical decisions are made, and false positives do occur, though they are less common with NIPT than with earlier serum screening methods.
For context on age-related chromosomal considerations more broadly, our article on prenatal care considerations after 35 addresses the fuller picture of older maternal age pregnancy.
Anatomy Ultrasound: Structural Screening
The anatomy ultrasound, typically performed around 18-22 weeks of pregnancy, evaluates fetal structural development and can identify a range of anatomical findings. It is not a chromosomal test but may reveal ultrasound markers associated with certain chromosomal conditions or structural anomalies. The anatomy scan is standard in prenatal care for all pregnant women and provides important information about fetal development across many dimensions.
Making Decisions About Prenatal Testing
Deciding which tests, if any, to pursue is a personal decision that depends on individual values, what information would be meaningful or actionable for you, and what you would do with different types of results. Some women find that information—even difficult information—allows them to prepare emotionally and make informed decisions. Others prefer not to know certain information, particularly if they would not consider pregnancy termination regardless of results.
There is no universally correct approach. What matters is that the decision reflects your own values and is made with accurate information rather than pressure in either direction. A genetic counselor—a specialist trained in helping people understand and navigate genetic testing—can be an invaluable resource for women who want to understand their options thoroughly before deciding. Many practices offer referrals to genetic counselors as part of prenatal care.
For more on the emotional aspects of navigating prenatal decisions after 35, our article on managing anxiety and uncertainty during pregnancy may also be helpful.
Frequently Asked Questions
Do I have to have genetic testing because I’m over 35?
No. Prenatal testing is offered to women, not required. ACOG’s guidance emphasizes informed decision-making—meaning your provider should offer testing and provide information to help you decide, but the decision is yours. Some women choose comprehensive testing; others choose selective testing or decline testing altogether. What matters is that your decision is genuinely informed and reflects your values.
What happens if a screening test comes back high-risk?
A high-risk screening result means the probability of a specific condition is estimated to be higher than a certain threshold—it does not mean the pregnancy is definitively affected. The next step is typically a referral for genetic counseling and a discussion of whether diagnostic testing (CVS or amniocentesis) is appropriate. Many pregnancies flagged as high-risk on screening turn out to be chromosomally normal on diagnostic testing.
Is NIPT covered by insurance for women over 35?
Coverage varies by insurance plan and changes over time. Many plans do cover NIPT for women considered at elevated risk, which often includes women 35 and older. Checking with your insurance provider and your OB’s billing team before ordering testing can help avoid unexpected costs. If cost is a concern, discussing it with your provider—who may be able to suggest covered alternatives—is worthwhile.
What does a normal anatomy scan mean?
A normal anatomy scan means that the structures examined during the ultrasound appeared typical for gestational age. It is reassuring, but it cannot detect all possible fetal conditions. Certain genetic syndromes and many smaller structural differences may not be visible on ultrasound. The anatomy scan is one piece of prenatal evaluation rather than a comprehensive clearance of all possible concerns.
Should I see a genetic counselor?
Many women pregnant after 35 find genetic counseling helpful, particularly if they want to understand their testing options thoroughly, have had a prior pregnancy affected by a chromosomal condition, or receive a screening result that requires interpretation. Genetic counselors are trained to explain probabilities and testing options in accessible terms and to support decision-making without pushing a particular choice. Many OB practices routinely offer genetic counseling referrals; if yours doesn’t, you can ask for one.
Key Takeaways
- ACOG now recommends offering prenatal screening to all pregnant women regardless of age, though older maternal age does increase the probability of certain chromosomal findings, which influences how test results are interpreted.
- There is an important distinction between screening tests (which estimate probability) and diagnostic tests (which provide definitive chromosomal answers but carry small procedural risks); understanding this distinction is essential for interpreting results.
- NIPT has high detection rates for the main trisomies and is widely used in pregnancies of women 35 and older, though positive results always require diagnostic confirmation before decisions are made.
- Decisions about prenatal testing are personal and should reflect individual values around information and decision-making; there is no universally correct choice.
- Genetic counselors are a valuable resource for women who want comprehensive support in understanding and navigating prenatal testing options; asking for a referral is entirely appropriate.
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.