Non-invasive prenatal testing (NIPT) is a simple and safe way to screen your baby’s DNA for common genetic conditions, such as Down syndrome, trisomy 18, and trisomy 13, early in pregnancy. It’s accurate, safe, and can even reveal your baby’s sex.
However, sometimes the results of an NIPT test are labeled as “inconclusive” or “no result,” meaning it doesn’t provide a clear answer. That can leave you wondering: How common is an inconclusive NIPT result?
In this article, we’ll answer that question and explain the reasons behind inconclusive results, what they might mean for your pregnancy, and the steps you can take if your test doesn’t provide a definitive answer.
How common is an inconclusive NIPT result?
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Inconclusive NIPT results occur in approximately 2–3% of all tests. While this is a relatively small percentage, it still affects a notable number of expectant parents. An inconclusive result means the test was unable to provide a clear yes-or-no answer about the risk for certain genetic conditions.
While it may be unsettling, this doesn’t automatically mean there’s a problem with the baby. Most often, this is a result of problems or challenges in the testing process or biological factors that make it harder to get a clear reading.
Why do inconclusive NIPT results happen?
There are different factors that can cause an NIPT result to come back inconclusive. The most common reasons are outlined in the following table:
Factor | How it can lead to an inconclusive result |
|---|---|
Low fetal fraction | This means there isn’t enough cell-free DNA (cfDNA) — your baby’s DNA — in your bloodstream for the test to work properly. Labs typically need at least 4% fetal DNA to get a clear result. If the test was done early in your pregnancy, or there wasn’t enough fetal DNA that day, the lab may not be able to assess risk accurately. |
Maternal weight | A higher body mass index (BMI) can dilute fetal DNA levels in your blood. This doesn’t mean anything is wrong; it just makes the test signal harder to detect. |
IVF or twin pregnancies | If you’re pregnant with multiples or conceived through IVF, there may be additional fetal or placental DNA in your blood. This can make it more challenging for the lab to interpret the results clearly, sometimes leading to an inconclusive outcome. |
Maternal health factors | Certain medical conditions — like autoimmune disorders or, very rarely, undiagnosed cancers — can affect the DNA in your blood and interfere with the test. |
Placental DNA differences | Sometimes, the DNA in the placenta doesn’t perfectly match your baby’s. This is called confined placental mosaicism and can cause the test to come back inconclusive, or even give a false positive or false negative. |
Lab or technical issues | Occasionally, the result is due to a problem with the blood sample, such as degradation or a handling error. While uncommon, it’s one reason why it’s important to test with a reputable lab. |
Even if the reason behind your inconclusive result isn’t immediately clear, identifying the likely cause helps guide what happens next. In many cases, it’s just a matter of timing, and repeating the test a bit later can bring more clarity. Either way, your care team will help you make sense of it and decide the best next steps.
Your options after an inconclusive NIPT result
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If you’ve received inconclusive NIPT results — whether it’s your first test or a repeat — you’re not alone. There are several paths you can take to gain more clarity about your baby’s health. Here’s a quick overview of your options:
Repeat the NIPT test
Undergo other non-invasive tests
Opt for diagnostic testing
Undergo an anatomical ultrasound
Request a chromosome study after birth
Explore whole-genome carrier screening
1. Repeat the NIPT test
In many cases, your healthcare provider may recommend repeating the test. This typically happens because the amount of fetal DNA in your bloodstream increases as your pregnancy progresses, which improves test accuracy. If your initial test had a low fetal fraction, waiting a few weeks and retesting can often provide the clear results you need without rushing into more invasive procedures.
Timing is important: repeating too soon may yield the same inconclusive result, but delaying too long could limit your choices later in pregnancy.
2. Undergo other non-invasive screening
If you're not carrying multiples, additional screening options, such as enhanced first-trimester or second-trimester screening, are also often recommended when your NIPT returns an inconclusive result. These tests combine blood markers with ultrasound measurements to estimate the risk of chromosomal abnormalities.
While less sensitive than NIPT, these tests can still offer meaningful risk assessments, especially when NIPT is inconclusive due to biological factors like multiple pregnancies or maternal weight. These screenings can help guide decisions about whether to pursue more definitive diagnostic tests.
3. Opt for diagnostic testing
If a repeat NIPT remains inconclusive or your provider suggests moving directly to diagnostic testing, this approach offers the most definitive answers by examining your baby’s chromosomes directly. Diagnostic procedures provide clarity when screening tests can’t, though they are more invasive and carry some risks.
The two main diagnostic options include:
Chorionic villus sampling (CVS): Typically done between 10 and 13 weeks, CVS involves taking a small sample of placental tissue for genetic analysis. It can provide early results but carries a slight risk of miscarriage and may not detect all conditions.
Amniocentesis: Usually performed after 15 weeks, this test samples amniotic fluid surrounding the baby. It has a slightly lower miscarriage risk than CVS and offers highly accurate results.
Choosing diagnostic testing allows you and your healthcare team to make informed decisions based on clear genetic information. While it involves more risk than non-invasive screening, it removes much of the uncertainty that an inconclusive NIPT result can cause.
4. Undergo an anatomical ultrasound
Source: MART PRODUCTION
The mid-pregnancy anatomy scan — typically performed between 18 and 22 weeks — becomes especially important when earlier genetic screening hasn’t provided clear answers. This detailed ultrasound evaluates your baby’s organs, limbs, and overall development, and can sometimes uncover signs that hint at underlying genetic differences.
An ultrasound can help identify:
Structural anomalies that might suggest a chromosomal condition
Placental abnormalities that could interfere with screening results
Fetal sex, if that wasn’t determined by NIPT
While it won’t confirm or rule out genetic conditions on its own, this scan adds valuable information that can help guide your next steps. Diagnostic testing like amniocentesis is usually performed earlier, but many patients wait for the anatomy scan before deciding whether to proceed with more invasive options.
5. Request a chromosome study after birth
If you prefer to avoid invasive prenatal procedures or if earlier screenings haven’t raised significant concerns, you may choose to wait and pursue genetic testing after your baby is born. Postnatal chromosome analysis is typically done using a blood sample from your newborn and offers a definitive way to check for chromosomal conditions.
This option may be appropriate when:
No abnormalities were detected on ultrasound
There’s no urgent medical reason to diagnose during pregnancy
You and your provider agree that the benefits of invasive testing don’t outweigh the risks in your case
While waiting means you won’t have genetic information during pregnancy, it allows you to avoid the risks of invasive prenatal procedures. If your baby shows any symptoms at birth or if there's a family history of genetic conditions, this kind of testing can help provide clarity and guide next steps.
6. Explore whole-genome carrier screening
Carrier screening identifies inherited genetic conditions that NIPT typically doesn’t detect, such as rare recessive disorders or conditions that might affect your baby’s health beyond chromosomal abnormalities. While often performed before conception, carrier screening during pregnancy can reveal risks that influence prenatal care choices or prepare you for potential challenges after birth.
Whole-genome carrier screening is even more beneficial as it analyzes all your genes, not just a select panel. This increases the chance of finding rare but important inherited conditions that standard carrier tests might miss. With this information, you and your provider can tailor monitoring plans, anticipate specific medical needs, and make more informed decisions throughout your pregnancy.
Platforms like Nucleus provide whole-genome testing with expanded gene coverage and detailed interpretation. If your NIPT results were inconclusive, whole-genome carrier screening with Nucleus can help fill in the gaps and guide your next steps.
Whole-genome carrier screening may be helpful for parents who want deeper insight into inherited risks, especially after receiving inconclusive results.
Nucleus: A comprehensive genetic screening option for family planning
Nucleus is a whole-genome sequencing (WGS) test that screens for over 900 inherited conditions, helping parents understand potential genetic risks and make confident decisions about their family’s future. Nucleus was designed to give you more complete information than typical carrier screening panels, which is especially helpful if you’ve had inconclusive results or want to plan with greater confidence.
Here’s how Nucleus can support you:
Carrier screening made simple: With quick, at-home cheek swabs, Nucleus checks whether you or your partner carry genes linked to inherited conditions.
Partner testing: Both you and your partner can test together, so you get a clearer picture of shared risks within a single platform.
Clear, easy-to-understand reports: Instead of overwhelming technical data, Nucleus provides straightforward summaries that explain what the results mean for you and your family’s health.
Genetic counseling included: Through a partnership with SteadyMD, you can connect with board-certified genetic counselors who can help you understand your results and make informed choices.
Privacy and accuracy you can trust: Nucleus is HIPAA and CAP-CLIA certified. It meets high standards for clinical-grade testing and data security, so your information stays confidential and reliable.
If your NIPT results were inconclusive or you want a more detailed understanding of inherited risks, Nucleus could be a valuable part of your next steps.
How to get started with Nucleus
Getting started with Nucleus is easy:
Provide your information
Place your order
Once you have your kit, collect your sample by swabbing your cheeks, and ship it back with the prepaid label. Your results will be available in 6–8 weeks.
The full service costs $499 ($798 for both partners) and includes the test kit(s), shipping, and detailed reports. Nucleus is also HSA/FSA eligible, making it more accessible for many families.
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