No doubt you’re anxious to see your growing baby — after all, nine months is a long time to wait to catch a glimpse of those tiny fingers and toes. And since 3D ultrasounds and 4D sonograms allow you to see your unborn baby in even more depth and detail than a standard ultrasound, you may be eager to book a photo op.
But before you do, it’s important to understand what 3D sonograms and 4D ultrasounds are, when they're used during pregnancy (if at all), how much they cost, and — most importantly — whether they're safe for you and your baby.
What is a 3D ultrasound?
A 3D ultrasound is exactly what it sounds like: one that produces three-dimensional photos of your baby.
During a 3D ultrasound, a wand (transducer) takes multiple two-dimensional images at various angles. The ultrasound machine then pieces them together to form a three-dimensional rendering.[1]
The actual procedure is similar to that of a standard 2D ultrasound, but the machine produces sharper, clearer and more detailed photographs. Instead of just seeing a profile view of your cutie’s face (think of an old-school Mickey Mouse cartoon), you’ll see the whole surface — it looks more like a character in a Pixar movie ... or a regular photo.
Your practitioner may opt for a 3D ultrasound if there are "uncertain" findings on a 2D ultrasound and they’d like a more comprehensive picture of your baby, says Shannon Smith, M.D., a board-certified OB/GYN and partner at Brigham Faulkner OB/GYN Associates in Boston, Massachusetts.
"A 3D image can better demonstrate abnormalities detected on 2D imaging, especially of the face, and skeletal and central nervous systems,” she explains.
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Because 3D ultrasounds are really only necessary if there’s a suspected fetal anomaly, “the vast majority are performed solely as a courtesy to patients,” says Dr. Smith, who is affiliated with Brigham and Women’s Hospital in Boston.
What is a 4D ultrasound?
A 4D ultrasound is similar to a 3D ultrasound, but the image shows movement, like a video. In a 4D sonogram, you'd see your baby doing things in real time (like opening and closing his eyes and sucking his thumb).
While 4D ultrasound "has been used to study the fetal heart, fetal movement, and fetal behavioral states,” says Dr. Smith, "there are no specific indications for ordering or recommending a 4D ultrasound.”
That means your doctor will likely only do a 4D ultrasound if you ask for one.
Are 3D ultrasounds and 4D ultrasounds safe?
Although in general, "ultrasound technology is safe," says Dr. Smith, she doesn't recommend booking an appointment for a non-medical 3D or 4D sonogram at your local prenatal portrait center for keepsake purposes.
Experts at the American College of Obstetricians and Gynecologists (ACOG) and the Food & Drug Administration (FDA) say that ultrasounds should only be performed by a qualified medical professional when your practitioner deems them necessary or gives you the okay.
Ultrasound technology has been used for more than 20 years and generally "has an excellent safety record," says the FDA. But when ultrasound enters the body, it warms the tissues a bit — which, in turn, "can also produce small pockets of gas in fluids or tissues" in some cases, the long-term effects of which are unknown.[2]
"Keepsake images or videos are reasonable if they are produced during a medically-indicated exam, and if no additional exposure is required," the FDA adds. "But the use of ultrasound solely for non-medical purposes such as obtaining fetal ‘keepsake’ videos has been discouraged."
ACOG currently recommends that expecting women have at least one 2D ultrasound between weeks 18 and 22 of pregnancy.[3] Many pregnant moms have more, for a whole host of reasons.
These groups also discourage the use of any kinds of ultrasounds (2D, Doppler, 3D and 4D) for the purpose of creating a memento.
That's because the technicians who perform commercial ultrasounds may not be able to address your questions or concerns the way your health provider could, and likely won’t have the expertise to be able to spot any problems with your baby’s development.
What's more, some commercial sessions last for 45 minutes — much longer than a medical scan. A long session (or repeat sessions, as some of these centers offer) can be intrusive and disruptive to a fetus who's using womb time to grow, develop and get enough sleep.
The same thinking goes for at-home Doppler ultrasound machines, which aren't nearly sensitive enough to pick up on fetal cardiac activity until the fifth month of pregnancy (and the FDA requires a prescription to use them).
If you’re considering getting any type of ultrasound outside of a medical setting, check with your practitioner first. If you do get the okay, try to limit your visits to one or two, with each scan no more than 15 minutes in length if possible.
Other ultrasounds and fetal monitoring
2D ultrasounds
If you’ve visited the doctor, you’ve probably already experienced a 2D ultrasound and know that it can be a pretty exciting, magical experience.
For this exam, a transducer is placed on your belly or into your vagina to send sound waves through your body. The waves bounce off internal organs and fluids, and a computer converts these echoes into a two-dimensional image (or a cross-sectional view) of the fetus on a screen. The resulting photo is a flat black-and-white image.
Doppler
With Doppler fetal ultrasound, your practitioner uses a hand-held ultrasound device to amplify the sound of fetal cardiac activity with the help of a special jelly on your belly.
Nuchal translucency (NT)
The NT screening is a specific ultrasound that’s performed at the end of the first trimester, between weeks 10 and 13 of pregnancy. Doctors measure a portion of the back of baby’s neck known as the nuchal fold, which they use to help determine baby’s risk of having a genetic disorder. It’s frequently combined with a blood test and used to screen for several types of trisomy, including Down syndrome.
Non-stress test (NST)
During your third trimester, your practitioner may recommend an NST if you have certain complications or your due date has passed. You may be more likely to have an NST, for example, if you have gestational diabetes or low amniotic fluid levels.
The test, which takes roughly 20 to 40 minutes, ensures your baby is healthy and active. Your practitioner will wrap a stretchy band around your belly that has a Doppler transducer, to track your baby’s heart rate, and a pressure transducer, to measure your baby’s movements and your uterine contractions. You’ll sit back and relax while they monitor a graph of your baby’s vitals and activity.
Biophysical profile (BPP)
Another test that you might encounter in the third trimester, the BPP involves an NST plus other measurements, including amniotic fluid levels and baby’s muscle tone and breathing. You may need a BPP for a number of reasons, such as if you have complications like preeclampsia, are carrying twins, or your baby has fetal growth restriction.
The test, which lasts up to 30 minutes, involves the same band used in the NST test. The doctor will also run an ultrasound wand over your tummy to get a better picture of what’s going on inside your uterus.
How much is a 3D ultrasound or a 4D ultrasound?
If your doctor performs a 3D or 4D ultrasound, it should be covered by your insurance if you have it as part of basic prenatal care, though it depends on your situation and plan.
If you do wind up deciding to go to a stand-alone ultrasound clinic for a keepsake ultrasound, you can expect to pay between $100 to $400, depending on where you live, the clinic, and the package of options you choose.
When can you get a 3D or 4D ultrasound?
Because there are very few medical reasons to perform a 3D ultrasound (and none for a 4D ultrasound), there isn’t a standard recommended time to perform these scans.
If your doctor agrees to offer a 3D or 4D ultrasound as a professional courtesy to you, the ideal time to get them done is toward the end of your pregnancy when you can get "the best views of the baby,” says Dr. Smith — usually between week 28 and week 32.
Why ultrasounds are used during pregnancy
ACOG recommends that women with low-risk, complication-free pregnancies should have at least one ultrasound, between 18 weeks pregnant and week 22 of pregnancy.
Many practitioners perform additional ultrasounds, even in healthy and uncomplicated pregnancies. For example, your doctor might scan you at 7 to 10 weeks to verify your date of conception.
At 11 to 14 weeks, most doctors perform an NT exam, a standard screening that assesses baby’s risk of chromosomal abnormalities. In the third trimester, ultrasounds are usually done between 32 and 36 weeks for a peek at fetal growth and amniotic fluid levels, says Dr. Smith.
There are many reasons ultrasounds in general are performed throughout pregnancy, depending on the trimester, including:
- Confirming your estimated due date
- Making sure the pregnancy isn't ectopic and is in the uterus
- Confirming the number of babies in utero
- Making sure baby is developing properly and at the appropriate pace
- Checking and measuring baby's major organs, including the heart
- Assessing the placenta and umbilical cord
- Measuring the length of your cervix
- Measuring the size of your baby
- Checking amniotic fluid levels
- Ruling out certain birth defects
- Determining baby's sex
- Giving parents a look at baby and providing reassurance that all is going as it should be in the pregnancy
Medical practitioners use 2D and Doppler ultrasounds in uncomplicated pregnancies to examine the fetus, assess amniotic fluid, and make sure all is well with baby's development and growth, among other reasons.
Ultrasounds in 3D and 4D are performed only to closely examine suspected fetal anomalies, such as cleft lip and spinal cord issues, or to monitor something specific.
In other words, 3D sonograms and 4D ultrasounds are not part of routine prenatal exams — although many practitioners will perform 3D scans for curious parents, especially if asked.
Remember: There will be plenty of opportunities to take photos and make memories when your baby is born. In the meantime, try to keep ultrasounds limited to those recommended or offered by your practitioner ... and look forward to the day you can see your baby in person (no technology necessary!).
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