Understanding Your 12-Week NT Scan Results

Feeling worried after your 12-week scan? You’re not alone.

If you’ve just had your 12-week scan—or you're waiting for it—and you’ve heard terms like “nuchal translucency”, “NT measurement”, or “increased chance”, it’s completely normal to feel anxious. Many women leave the scan room with more questions than answers, wondering what the measurements mean and whether everything is okay.

As a registered obstetric sonographer, I’ve spoken to hundreds of expectant parents in your shoes. Let’s break it all down together in a calm, clear way—so you can understand what the results really mean and what comes next.

What is the NT scan and why is it done?

The NT (nuchal translucency) scan is part of the first-trimester screening usually offered between 11 weeks and 14 weeks + 1 day. It measures the fluid at the back of your baby’s neck—this fluid is called the nuchal translucency.

Why this matters: A thicker-than-expected measurement can be an early indicator of a higher chance of certain chromosomal conditions, like Down’s syndrome (trisomy 21), Edwards’ syndrome (trisomy 18), or Patau’s syndrome (trisomy 13). It can also be an early sign of the presence of heart conditions.

But—and this is really important—a high NT measurement does not mean there’s definitely something wrong. It simply means more information is needed to understand the full picture.

What is a normal NT measurement at 12 weeks?

This is one of the most common questions I get: “What should the NT measurement be?”

Here’s the general rule:

• Most babies at 12 weeks have an NT measurement between 1.2 mm and 2.5 mm
• Anything under 3.5 mm is generally considered within the normal range
• 3.5 mm or more is classed as increased and would likely prompt further testing

That said, NT measurements are interpreted alongside other factors—like the baby's crown-rump length (CRL), maternal age, and blood test results—to give a personalised, more accurate risk estimate.

Does an increased NT mean something is wrong?

Not necessarily.

An increased NT measurement may mean there’s a slightly increased chance of certain conditions, but many babies with raised NT measurements are born completely healthy.

Here’s what might happen next:

• You may be offered non-invasive prenatal testing (NIPT), which looks at fetal DNA in your blood
• Or you might be referred for further diagnostic tests like CVS (chorionic villus sampling) or amniocentesis
• You may also be offered an early detailed anatomy scan, depending on the NT measurement and your personal history

Why do some NT measurements look different at the same gestation?

Your baby’s exact gestation matters. NT thickness changes with fetal size and age—even a few days difference can affect the number. That’s why we also measure the crown-rump length (CRL), which helps us date the pregnancy and interpret NT results accurately.

Dating a pregnancy based on LMP (last menstrual period) isn’t always exact, especially if your cycles are irregular or if ovulation happened later than average. That is why CRL is used to 'officially' date pregnancies. It’s not a perfect science, but it’s the best we have.

What happens after a raised NT scan result?

If your baby's NT is 3.5mm or more, your care team may discuss:

• NIPT (Non-Invasive Prenatal Testing): A blood test that looks for fragments of your baby’s DNA. No risk to the baby.
• Diagnostic Tests: CVS or amniocentesis can give a definite answer but carry a small risk of miscarriage.
• Referral to Fetal Medicine: For detailed assessment if NT is significantly raised or if other signs are present.

These conversations can feel intense, but remember—you’re in control. You can say yes to some tests and no to others. You can ask for time, support, or a second opinion.

What does "low risk" or "high risk" actually mean?

Your result might be given as a ratio, like:

• 1 in 2000 = low chance
• 1 in 150 = higher chance

This isn’t a prediction. It’s a statistical estimate based on your age, baby’s measurements, and blood results.

Even with a “high risk” result, the baby is more likely to be healthy than not. It just means you're offered more information to explore further.

What if I don’t want further testing?

That’s completely your choice.

Some people choose not to go ahead with additional screening. Others want as much certainty as possible. There’s no right or wrong here—just what’s right for you and your values.

If you’re not sure, it’s okay to take your time. You can always come back to the decision later.

What does NT mean in the bigger picture?

NT is just one part of a complete picture of your baby’s health.

Even if the number seems slightly raised, it may be balanced out by other reassuring findings—such as normal bloodwork, a healthy CRL, and clear anatomy at your follow-up scans.

You are never expected to interpret this all on your own. That’s why midwives, fetal medicine specialists, and yes—sonographers like me—are here to help explain.

FAQ: NT Scan Results, Explained

You’re not alone—and you don’t need to figure this out on your own.

Your 12-week scan can bring up a lot of feelings—hope, excitement, anxiety. If something unexpected comes up, it’s natural to want answers. And it’s okay to need time, space, or a little extra support.

The fact that you’re here, reading and learning, tells me you care deeply. You’re doing everything right.

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