NIPT vs. amniocentesis: How they differ and when each is recommended

During pregnancy, you’ll likely hear about prenatal tests like NIPT and amniocentesis. It’s completely normal to feel unsure about which tests are necessary and why they’re recommended. Typically, your doctor would recommend NIPT and amniocentesis to give you a clearer picture of your child’s health so you can make informed decisions.

Though they’re often discussed together, NIPT and amniocentesis are distinct from each other. While both are used to detect genetic conditions, they vary in how they’re performed, what they screen for, and the level of accuracy they provide. Knowing these differences can help you feel more confident and informed when deciding which test, if either, is the better choice for you and your baby.

In this article, we’ll compare NIPT vs. amniocentesis, explore their accuracy and risks, and discuss why and when each might be recommended during pregnancy.

What is NIPT, and how does it work?

Non-invasive prenatal testing (NIPT) is a screening test that checks for certain chromosomal abnormalities in your baby. During the test, a small blood sample is drawn (usually from your arm) and sent to a lab for analysis.

The lab looks at tiny pieces of your baby’s DNA that are found in your blood. These pieces of DNA are known as cell-free DNA (cfDNA), which come from the placenta and circulate in your bloodstream during pregnancy.

NIPT is commonly used to screen for conditions like:

• Down syndrome (Trisomy 21)

• Edwards syndrome (Trisomy 18)

• Patau syndrome (Trisomy 13)

NIPT can also be used to predict the sex of your baby and check for certain sex chromosome conditions like Turner syndrome and Klinefelter syndrome. 

It’s important to remember that NIPT is a screening test, meaning it can tell you the likelihood that your baby has one of these chromosomal abnormalities, but it can't provide a definitive diagnosis. If the test shows a high risk, your doctor might recommend further testing, like amniocentesis or CVS, to confirm the results.

What is amniocentesis, and how does it work?

Amniocentesis is a diagnostic test that helps doctors determine if your baby has chromosomal abnormalities, such as Trisomy 21, 18, and 13. It can also be used to:

• Diagnose neural tube defects like spina bifida

• Assess your baby’s lung maturity, especially if there’s concern about early delivery

• Check for infections

The test works by analyzing the amniotic fluid — the fluid that surrounds and protects your baby in the womb. This fluid contains your baby’s cells and proteins, which provide valuable genetic information.

Here’s how the procedure is done:

1. You’ll be asked to lie on your back while the healthcare provider prepares for the procedure.

2. They will clean your abdomen with antiseptic and apply an ultrasound gel.

3. An ultrasound scan will be used to create images of the baby while they insert a thin needle into your uterus and the amniotic sac.

4. A small amount of your amniotic fluid will be extracted and sent for lab analysis.

Amniocentesis vs. NIPT: Seven factors that differentiate these prenatal tests

At first glance, NIPT and amniocentesis might seem like they’re doing the same thing — they’re both prenatal tests that check for chromosomal abnormalities like Trisomy 21 and 18. 

In reality, they work in very different ways and offer varying levels of certainty.

In the following sections, we’ll explore further what sets them apart, including:

1. The procedure used

2. The conditions screened

3. Accuracy

4. Purpose 

5. Timing 

6. Risk factors 

7. Result turnaround time

1. The procedure used 

Source: Kaboompics

When it comes to invasiveness, NIPT is the less invasive of the two tests. This is because it only requires a simple blood draw from the mother, which is then analyzed in a lab to isolate and examine the baby’s DNA.

Amniocentesis, on the other hand, is more invasive. During this procedure, your healthcare provider will insert a thin needle into your uterus to take a small sample of the amniotic fluid surrounding your baby. While it’s generally safe when performed by an experienced provider, the fact that it involves checking your uterus makes it more complex than a simple blood test like NIPT.

2. The conditions screened 

There are significant differences in the range of conditions that NIPT and amniocentesis can detect. Here’s a quick overview:

Both tests screen for chromosomal conditions — that’s why you’ll see overlap with conditions like Down and Edwards syndrome on both lists. Amniocentesis, however, can detect a broader range of conditions, including congenital abnormalities, neural tube defects like spina bifida, and fetal lung maturity, making it a more comprehensive test.

If you’re primarily concerned with chromosomal conditions, NIPT may be a good place to start, as it’s less invasive. But if you're looking for a more complete picture, amniocentesis offers that depth.

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3. Accuracy

Source: Edward Jenner

Since NIPT is a screening test, it’s not 100% accurate. There can be false positives (indicating a condition when the baby doesn’t have it) or false negatives (missing a condition that is present). 

Its accuracy also depends on the specific condition being screened. For Down syndrome, it’s about 99% accurate, but it’s less reliable for conditions like Edwards and Patau syndrome. Certain factors can affect the results as well, such as:

• High maternal BMI

• Being a surrogate

• Carrying multiples

Amniocentesis, in contrast, is a diagnostic test — which means it’s used to confirm conditions, not just screen for risk. It’s much more accurate, with an accuracy rate of up to 99%. 

That’s why amniocentesis often comes after screening tests like NIPT. If NIPT suggests a high risk for a chromosomal condition, many people choose to follow up with amniocentesis to get a clearer answer before moving forward with any decisions.

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That said, while amniocentesis can confirm whether a condition is present, it can’t tell you how severe that condition may be — something worth keeping in mind as you weigh your options.

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4. Purpose

NIPT is a screening test designed to give you an estimate of the risk that your baby has certain chromosomal abnormalities. It’s a helpful first step to assess whether further testing is needed. 

Amniocentesis, however, has a broader role. Besides diagnosing chromosomal and congenital abnormalities, it’s also used for treatment in certain situations. For example, in cases of polyhydramnios — a condition where there’s too much amniotic fluid around the baby — amniocentesis can help by removing some of the excess fluid. This can help reduce the risk of complications, such as preterm labor, and ease discomfort for the mother. 

5. Timing

The timing for when you can take NIPT and amniocentesis differs significantly during pregnancy.

NIPT is typically performed starting at 10 weeks of pregnancy. For the test to be effective, there needs to be enough fetal DNA in your bloodstream — at least 4%. If this threshold isn’t met, the results may be insufficient or inconclusive. In most cases, fetal DNA reaches this level around the 10th week, which is why it’s recommended to wait until then for the test.

Amniocentesis, on the other hand, is done later in pregnancy — usually between 15 and 20 weeks. This timing is crucial because performing the procedure too early increases the risk of miscarriage. For this reason, doctors generally recommend waiting until later in the second trimester to ensure both safety and accuracy.

6. Risk factors

Since NIPT involves providing a small blood sample, it’s a non-invasive test that carries very little risk. Most women experience no side effects beyond the usual discomfort of a blood draw, and there are no serious health risks associated with the procedure.

Amniocentesis, however, carries some risks due to its invasive nature. Though complications are rare, some women may experience cramping, mild discomfort, or leakage of amniotic fluid after the procedure. 

While the overall risk is low, there’s a small chance of miscarriage (about 1%), which is why it’s important to discuss the risks thoroughly with your doctor before proceeding with the test.

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7. Result turnaround time

The time it takes to receive results from NIPT and amniocentesis can vary based on the lab, but here’s a general idea of what you can expect:

If timing is a key factor for you, NIPT may be more appealing since you’ll typically get results within a week. On the other hand, amniocentesis requires more time — although you’ll get preliminary results in about three days, the final confirmation takes up to three weeks. For some, the wait might feel long, but for others, the ability to get definitive answers after that wait can provide reassurance.

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Amnio vs. NIPT: Which should you choose?

The choice comes down to how much certainty you want — and how quickly you want it.

NIPT is fast, simple, and low-risk. It’s a great starting point if you want early insight and are okay with following up if needed. Amniocentesis takes longer and carries more risk, but it offers a clear, confirmed diagnosis, which can be critical if there’s already a concern.

But here’s what often gets missed: while these tests give insight into the baby’s genetic health, they don’t account for your own. If you want to know whether you carry any genetic conditions that could affect this pregnancy (or future ones), you might need to get tested yourself.

That’s why many families are turning to carrier screening. Even if your baby’s results look fine now, there’s still the question of what risks might be hiding in your own DNA — gene variants that don’t affect you but could be passed on. Nucleus Family offers one of the most comprehensive options available — it screens for over 900 inherited conditions in a single test, offering a clear understanding of your genetic risks.

Planning for parenthood? Nucleus Family can provide clarity

Nucleus Family is a physician-ordered, clinical-grade test that screens for hundreds of inherited and genetic conditions to help you understand your potential genetic risks before and during pregnancy.

To help you and your partner make decisions based on clear, reliable information, Nucleus Family offers:

• Broad screening for inherited conditions: Screens for over 900 genetic conditions, including muscular dystrophy, hemophilia, and cystic fibrosis.

• Partner testing for a complete picture: Both partners can take the test, which gives you a full view of your combined genetic risks.

• Expert genetic counseling: Through Nucleus’ partnership with Steady MD, you get access to board-certified genetic counselors who can guide you through your results and reproductive options.

• Non-invasive testing: A simple cheek swab is enough to take the test — no need for blood tests or clinic visits.

Aside from being thorough, Nucleus Family is also fully regulated for privacy and accuracy. Nucleus is HIPAA-compliant and CAP-CLIA certified — you can trust that your results are accurate and your personal information is secure.

How to get started with Nucleus Family

Nucleus Family makes genetic testing easier than ever with its at-home cheek swab test. The process is non-invasive, quick, and hassle-free. Your kit comes with clear instructions and prepaid two-way shipping, so you can send your sample to the lab without any extra effort.

Get started with three simple steps:

1. Sign up for Nucleus Family

2. Fill in your personal details

3. Order your test kit

After sending your sample to Nucleus, your results will be available within six to eight weeks, complete with personalized reports and expert guidance.

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Featured image source: Pavel Danilyuk