A Brief Guide to SMFM’s Updated Prenatal Genetic Screening Recommendations

By: Britton D. Rink, MD, MS, and Barton C. Staat, MD

The Society for Maternal-Fetal Medicine (SMFM) recently released updated guidelines to help doctors and patients use cell-free DNA (cfDNA) screening more wisely. cfDNA screening is a blood test used during pregnancy to check for certain fetal genetic conditions. This screening test has been around since 2011 and is one of the most accurate ways to screen for fetal genetic conditions like Down syndrome.  

In a recent podcast, Drs. Britton D. Rink and Barton C. Staat explain what has changed with the guidelines on cfDNA screening and why it matters.  

Here is a breakdown of some key points from the podcast about the revised recommendations: 

Why Update the Guidelines Now? 

The last major update to the prenatal genetic screening guidelines was in 2020. Since then, the science of genetic screening has improved, and we have learned more about how cfDNA screening works in different situations. The new SMFM guidelines, endorsed by the American College of Obstetricians and Gynecologists (ACOG), help doctors give better advice that allows patients to make informed choices. 

What’s Changed? 

Some Tests Should Be Optional 

cfDNA is great at detecting common conditions like Down syndrome. When it comes to sex chromosome abnormalities (like Turner syndrome), however, there is a higher chance for false positive results, and it is possible for an unexpected sex chromosome difference to be discovered in the pregnant person. This can happen if the test picks up something in the pregnant person’s DNA instead of in the DNA of the fetus.  

Because of this, SMFM recommends that screening for sex chromosome differences should be optional. Patients should talk with their doctor and decide if they want this part of the test.

Rare Conditions: Not for Routine Testing 

Some labs offer cfDNA tests for rare genetic conditions in the fetus called microdeletions. These microdeletions are small missing pieces of DNA that can cause health problems, but these conditions are rare. The rarer a disease, the more likely that a screening test will have a false positive result. 

SMFM recommends against routine cfDNA screening for these rare conditions. If parents are concerned, they should talk with a genetic counselor and consider more detailed tests. 

Screening in Pregnancies with Twins and Multiples 

Although cfDNA works well for detecting Down syndrome in twin pregnancies, it is not recommended for pregnancies with triplets or more. Screening for sex chromosome differences in any multiple pregnancy is not recommended.

What If the Test Does Not Work? 

Sometimes, cfDNA tests come back as “non-reportable” which means the lab could not get a clear result. This can happen if: 

• The test is done too early in pregnancy 
• There is not enough fetal DNA in the sample 
• The pregnant person’s weight, fibroids, or medications affect the result 

A non-reportable result might mean a higher chance of a genetic condition. When this happens, doctors should offer patients a follow-up ultrasound, genetic counseling, and possibly a more detailed test. 

False Alarms Can Happen 

Sometimes the cfDNA screening test indicates there is a genetic problem with the fetus when there is not one. This can happen because of: 

• A twin that did not survive early in pregnancy 
• Mosaicism in the placenta  
• A health condition in the pregnant person 
• Uterine fibroids 
• Lab errors

SMFM recommends that patients meet with a genetic counselor or physician with expertise in genetic screening to help understand a high-risk result. 

Why Communication Matters 

One of the most important messages from the new guidelines is the need for a conversation before prenatal screening is performed. Patients should understand: 

• What the test can and cannot tell them 
• The cost of the test  
• What happens if the result is unclear or unexpected 
• That they can choose to have screening, skip genetic testing altogether, or go straight to diagnostic testing 

Thorough counseling on prenatal screening helps avoid surprises and gives patients more control over their care.

Three Important Takeaways 

Here are three things to remember: 

• cfDNA is a powerful tool, but it is not a diagnostic test — and it is not the right choice for everyone. 
• Some parts of the test should be optional, especially for rare conditions or sex chromosome differences. 
• A conversation between patients and healthcare providers before testing is important. 

Whether you are an expectant parent or a healthcare provider, these new guidelines are about making prenatal care more thoughtful, accurate, and supportive. 

Read SMFM Consult Series #74 Cell-free DNA screening for aneuploidies: Updated guidance here.  

Listen to the SMFM Podcast: Cell-Free DNA. 

 
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Britton D. Rink, MD, MS, is on the SMFM Board of Directors and is director of Medical Genetics at Mount Carmel Healthcare System in Columbus, OH. She also practices pediatric clinical genetics at Nationwide Children’s Hospital, also in Columbus. Barton C. Staat, MD, is a Colonel in the Air Force and chair of the department of ob/gyn at the Uniformed Services University of the Health Sciences in Bethesda, MD. Dr. Staat also serves as the Air Force Surgeon General Consultant for Maternal-Fetal Medicine.