By Sarina Gomez
This article is general information, not medical advice. Ask your midwife, OB-GYN or sonographer about your own pregnancy and scans.
For a 3D picture that looks like a baby’s face, the late second and early third trimester usually works best, roughly 26 to 30 weeks. Before that the face has little fat and looks thin and bony; after about 32 weeks the baby is bigger, has less room to turn and can hide the face. Keep in mind that the FDA and the AIUM discourage ultrasound done only for keepsake pictures, so the safest 3D image is one taken during a scan you already need.
Why timing changes the face so much
A 3D ultrasound draws the surface of your baby from echoes, so the picture shows exactly what’s under the skin at that week. Two things change fast in the second half of pregnancy:
- Fat. ACOG’s week-by-week guide says fat starts forming under the skin at 21 to 24 weeks, and that between 25 and 28 weeks the skin begins to look smoother as more fat is added. MedlinePlus adds that at 31 to 34 weeks the baby “grows quickly and gains a lot of fat.”
- Space. The baby grows from about 9 to 10 inches at 20 weeks to about 17 to 18 inches by 32 weeks, according to Cleveland Clinic. The uterus grows too, but a bigger baby has fewer ways to turn its face toward the probe.
Fluid matters as well. The software needs a pocket of amniotic fluid in front of the face to see the skin. MedlinePlus notes the amount of fluid is greatest at about 34 weeks, so fluid alone isn’t what makes late scans harder; the baby’s size and position are.
Week by week: what a 3D face shows from 16 to 34 weeks
Here is what to expect at each stage, based on how the baby develops. Individual scans vary a lot with position and placenta.
| Weeks | What’s developing | What a 3D face usually looks like |
|---|---|---|
| 16–19 | Skin is thin and see-through; ears, nose and lips become recognizable around 17–20 weeks | Small and skeletal; features are there but sharp-edged |
| 20–22 | The anatomy scan window; fine lanugo hair covers the body | Thin and bony; the shape of the skull and cheekbones shows through |
| 23–25 | Fat starts to form; skin is wrinkled and reddish | Features fill in a little; still lean |
| 26–28 | Skin looks smoother as fat is added; eyelids can open and close | Cheeks begin to round out; often the first “baby-like” face |
| 29–32 | Rapid fat gain; the head may have some hair | Full cheeks and lips, closest to a newborn look, if the baby faces the probe |
| 33–34 | Limbs look chubby; the baby may settle head-down for birth | Very round face, but often squashed against the wall, the placenta or a hand |
Development stages from ACOG and MedlinePlus.
Why 20 weeks looks bony. At the anatomy scan, the face has its features but almost no fat under the skin, so a 3D rendering shows the shape of the bones underneath. That’s normal development, not a sign of anything about how your baby will look. Our guide to the 20-week anatomy scan covers what that scan is really for.
Why 26 to 30 weeks looks round. By then the skin is smoother and fat is building in the cheeks, while there’s still room to turn. A 2023 study presented to the British Medical Ultrasound Society rated 342 3D face images taken at 21 to 30 weeks and found gestational age linked to image quality, along with fluid in front of the face, a posterior placenta and the baby’s position. It’s a small study, but it matches the common studio advice to book in this window.
The usual window for keepsake 3D and 4D scans
Elective studios commonly suggest booking around 26 to 32 weeks, for the reasons above. The same timing applies to 4D, which is 3D shown in motion; our comparison of 3D vs 4D ultrasound explains what each gives you to take home.
If you’re having twins, a baby in a breech position or a placenta at the front, ask the clinic whether they suggest a different week. A front (anterior) placenta doesn’t rule out a picture, but it can sit between the probe and the face.
Before you book, weigh the safety advice. No evidence shows that ultrasound harms a fetus, and the main bodies still advise against scanning only for pictures:
- ACOG: “There is no evidence that ultrasound is harmful to a developing fetus,” but exams should be done only for medical reasons by qualified professionals (ACOG).
- FDA: Using ultrasound only for keepsake videos “has been discouraged”; keepsake images are reasonable if they’re produced during a medically indicated exam and no additional exposure is required (FDA).
- AIUM: Ultrasound without a medical reason, only to view the fetus, is “inappropriate and contrary to responsible medical practice,” and the AIUM encourages sharing images during medically indicated scans (AIUM).
The lowest-exposure route is to ask, at any scan you’re already having in that window, whether the sonographer can try a 3D view for a minute. Not every machine or clinic offers it, but it costs nothing to ask. If you choose a studio anyway, ask who scans, what training they have and how long the session lasts. Our keepsake ultrasound safety guide lists the questions.
How to get the clearest picture on the day
Timing is the factor you control; the rest depends on the baby. A few things help:
- Book for the week, then be flexible. If the baby is face-down or hiding behind a hand, ask whether you can come back.
- Move between tries. The NHS says that if a baby isn’t in a good position, you may be asked to walk around and come back after a short break.
- Ask about the placenta first. If your records note an anterior placenta, ask the clinic whether that changes their advice.
Our full checklist is in how to get clear 3D ultrasound pictures, and our 3D ultrasound guide explains how the picture is made.
If you only have a 2D or early scan
Most parents never get a 3D scan, and the pictures they take home are 2D. If you’d like to imagine the face from what you already have, SeeMyBaby turns one photo of your scan into an imagined newborn portrait in about a minute. A clear 3D profile from the 26-to-30-week window gives the closest result; a 2D scan still works, but the portrait is more imagined. It’s a fun guess, not a prediction or a medical reading of the scan.
Wondering about other details on a 3D picture? See whether you can really spot hair on a 3D ultrasound.
Sources
- American College of Obstetricians and Gynecologists: How Your Fetus Grows During Pregnancy and Ultrasound Exams
- MedlinePlus: Fetal development and Amniotic fluid
- Cleveland Clinic: Fetal development: stages of growth
- U.S. Food and Drug Administration: Ultrasound Imaging
- American Institute of Ultrasound in Medicine: Prudent Use and Safety of Diagnostic Ultrasound in Pregnancy
- British Medical Ultrasound Society: Quantitative evaluation of factors influencing the acquisition of 3D obstetric US images (poster, 2023)
- NHS: 20-week screening scan
More scan guides are on the SeeMyBaby blog.
Questions parents ask
Can you do a 3D ultrasound at 20 weeks?
Yes, and some hospitals add a 3D view at the anatomy scan. The face usually looks thin and bony at that stage because fat hasn’t built up under the skin yet.
Is 28 weeks a good time for a 3D ultrasound?
It’s in the window most studios suggest. By 25 to 28 weeks, ACOG says the skin begins to look smoother as fat is added, and the baby usually still has room to turn.
Is 34 weeks too late for a 3D ultrasound?
Not too late, but harder. The face is at its roundest, yet the baby has less room to turn and may be settling head-down, so the face is more often pressed against something.
When is the best time to get a 4D ultrasound?
The same window as 3D, roughly 26 to 30 weeks, since 4D is 3D shown in motion. The same FDA and AIUM advice against scanning only for keepsakes applies.
Also available in: Deutsch · العربية · Español · Français · Italiano · 日本語 · 한국어 · Português (Brasil)
