No doubt you’re anxious to see your growing baby in your belly — after all, nine months is a long time to wait to catch a glimpse of those tiny fingers and toes. And since 3D and 4D ultrasound exams allow you to see your unborn baby in even more depth and detail than a standard 2D ultrasound, you may be eager to book a photo op.

But before you do, it’s important to understand when 3D sonograms and 4D sonograms should be used during pregnancy to ensure you’re doing everything possible to keep you and your baby safe and healthy.

What’s the difference between 2D, Doppler, 3D and 4D ultrasounds?

During your pregnancy, you may receive a combination of the following ultrasounds:

2D ultrasounds 

If you’ve visited the doctor, you’ve probably already experienced a 2D (two-dimensional) ultrasound and know it can be an exciting and magical moment.

For this exam, a wand (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.


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.

3D ultrasounds 

For 3D ultrasounds, multiple two-dimensional images are taken at various angles and then pieced together to form a three-dimensional rendering. For instance, instead of just seeing a profile view of your cutie’s face, in a 3D sonogram you can see the whole surface (it looks more like a regular photo).

4D ultrasounds 

A 4D ultrasound is similar to a 3D ultrasound, but the image shows movement like a video would. So in a 4D sonogram, you'd see your baby doing things in real time (like opening and closing his eyes and sucking his thumb).

Reasons to get ultrasounds during pregnancy

Women with low-risk, complication-free pregnancies will typically have at least one ultrasound, while older moms and those with complications will usually have more. There are many reasons ultrasounds in general are necessary during pregnancy, depending on the trimester, including:

  • Confirming your estimated due date
  • Making sure the pregnancy isn't ectopic (i.e. in the Fallopian tubes) 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
  • 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

Why 3D and 4D sonograms are performed during pregnancy

Medical practitioners use 2D and Doppler ultrasounds in uncomplicated pregnancies to examine the fetus, assess amniotic fluid and look for birth defects, 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 usually not part of routine prenatal exams.

Are 3D and 4D ultrasounds safe during pregnancy?

It's tempting to book an appointment for a 3D or 4D sonogram at your local prenatal portrait center, especially if you've seen these stunning baby portraits and videos online. But studies evaluating the safety of ultrasound technology show mixed results.

At this point, the American College of Obstetricians and Gynecologists (ACOG) says that while there are no known risks of ultrasounds for pregnant women, they should be used carefully and only for medical purposes. According to the Food and Drug Administration (FDA), when ultrasound enters the body it heats the tissues slightly, which in some cases can create small pockets of gas in body fluids or tissues — and the long-term effects of this are unknown.

Given what we do know, experts (including ACOG and the FDA) say that ultrasounds should only be performed by a qualified medical professional when your practitioner deems them necessary for medical reasons. Currently, ACOG recommends that expecting women have at least one 2D ultrasound between weeks 18 to 22 of pregnancy, noting that some women may also have a first-trimester ultrasound.

Experts also discourage the use of any kinds of ultrasounds (2D, Doppler, 3D and 4D) for the purpose of creating a memento. That's because, in addition to potentially putting your baby’s health at risk, the technicians who perform commercial ultrasounds may not be able to address your questions 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 for a fetus who's using womb time to grow, develop and get the sleep he needs.

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. Bring your wallet, too. Some studios charge a hefty price for that photo of your baby.

Remember: There will be plenty of opportunities to take photos and make memories when your baby is born. In the meantime, keep ultrasounds to a minimum and look forward to the day you can see your baby in person (no technology necessary!).