3D vs 4D Ultrasound: Differences, Timing and Which to Pick

This article is general information, not medical advice. Ask your midwife, OB-GYN or sonographer about your own pregnancy and scans.

A 3D ultrasound is a still, shaded image of your baby’s surface; a 4D ultrasound is the same kind of image shown in motion, like a short video. The FDA puts it simply: 3D “allows the visualization of some facial features”, and 4D is 3D ultrasound in motion. If you mainly want a face picture to keep, a good 3D still is what you’ll print and frame. 4D adds yawns and stretches, but not more detail.

2D, 3D, 4D, 5D and 8K side by side

Only 2D, 3D and 4D describe how the ultrasound is captured and shown. 5D (often sold as HD Live) and 8K are about how the image is shaded or redrawn afterwards.

Two things to notice. First, every type after 2D still depends on the same echoes, so a baby facing the wall or hiding behind a hand gives a poor picture in all of them. Second, the further down the table, the more of the image comes from software rather than from your baby. Our 8K ultrasound explainer covers that last row in detail.

What 3D and 4D are used for medically

In medical care, 2D is the workhorse and 3D is a specialist tool. ACOG lists 3-D ultrasonography among the techniques used in a specialized exam when a problem is suspected, while the standard exam everyone should have is done at 18 to 22 weeks. RadiologyInfo notes that some physicians also use 3D to check whether the baby is developing normally.

So if your provider offers a 3D view during a medical scan, it’s because it helps answer a question. If you’re paying a studio for 3D or 4D, it’s a keepsake, and it doesn’t replace the anatomy scan. Our 20 week anatomy scan guide explains what that medical exam covers.

Keepsake 3D and 4D scans: what the experts say

The professional bodies discourage scans done only for pictures. The FDA says keepsake images are reasonable when produced during a medically indicated exam, but that ultrasound used “solely for non-medical purposes such as obtaining fetal ‘keepsake’ videos has been discouraged,” because ultrasound can slightly heat tissue and the long-term effects “are still unknown.”

ACOG says there’s currently no evidence that ultrasound harms a developing baby, but recommends it be done only for medical reasons by qualified professionals, and that casual use be avoided. The AIUM encourages clinics to share images with parents during medical exams and asks parents to check that whoever scans them has formal training in fetal imaging.

If you decide on an elective scan anyway, ask who will scan you, what training they have, and how long the session lasts. A shorter session with a trained sonographer is the sensible choice.

When to get a 3D or 4D ultrasound

For a face picture, the middle-to-late second trimester into the early third is when the face has enough shape. ACOG’s week-by-week guide says ears, nose and lips become recognizable on ultrasound at around 17 to 20 weeks, fat starts forming under the skin at 21 to 24 weeks, and skin looks smoother as more fat is added at 25 to 28 weeks. Many elective studios suggest booking somewhere around 26 to 32 weeks for that reason.

A small 2023 study of 342 3D facial images presented at the British Medical Ultrasound Society found that gestational age, fluid around the face, placental position, the baby’s position and limbs blocking the face all affected image quality. Our guide to the best time for a 3D ultrasound goes week by week.

Which one should you pick?

Choose by what you want to take home, not by the biggest number on the price list.

• You want one lovely face picture to frame: 3D. A clear still is the thing people print.
• You want to see movement and share a clip with family: 4D. Ask for stills from the session too.
• You want the warmest, most lifelike look: 3D/4D with HD Live-style shading, if the clinic has it.
• You only have a 2D scan and no plans for another: keep your 2D pictures and enjoy them. Read our guide to getting clear 3D ultrasound pictures if you do book one.

Turning the picture you have into a portrait

You don’t need a new scan to imagine your baby’s face. SeeMyBaby turns one photo of your 2D, 3D or 4D scan into an imagined newborn portrait in about a minute. A clear 3D or 4D scan with a visible profile gives the closest result. A 2D scan still works, but the result is more imagined. It’s for fun, not a prediction or a medical view, and it can’t show more than your scan does.

If you’re comparing your 3D scan with your newborn later, our article on 3D ultrasound vs the real baby explains the differences. There’s more on scans in the blog, including our 3D ultrasound guide and 4D ultrasound guide.

Sources

• FDA: Ultrasound Imaging
• ACOG: Ultrasound Exams
• ACOG: How Your Fetus Grows During Pregnancy
• AIUM: Official statements, keepsake fetal imaging
• RadiologyInfo (ACR/RSNA): Obstetric Ultrasound
• BMUS 2023 poster: Factors influencing 3D fetal facial images

Questions parents ask

Is 4D better than 3D ultrasound?

Not in detail. 4D shows the same type of image as 3D, in motion. It’s better for watching movement, while a 3D still is usually what people print.

What is the difference between 2D, 3D and 4D ultrasound?

2D shows flat black-and-white slices used for medical checks. 3D builds a shaded surface image, and 4D shows that 3D image moving in real time.

Is 5D ultrasound real?

5D is a marketing name for 3D/4D with newer, more lifelike shading, such as a virtual light source. It isn’t a separate kind of scan.

Are 3D and 4D ultrasounds safe?

ACOG says there’s no evidence ultrasound harms a developing baby but recommends scans only for medical reasons. The FDA discourages ultrasound used just for keepsakes.

Sarina GomezEditor, SeeMyBaby

Sarina Gomez is the pen name of the SeeMyBaby editorial team.

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