Ultrasounds in Pregnancy: Procedure, Schedule, & Safety

For many expectant parents, pregnancy starts to feel real the first time they see their baby on a screen.

Pregnancy ultrasounds are a standard part of modern prenatal care. They’re more than just a chance for a sneak peek at your baby; ultrasounds help your doctor check on her development and ensure that both of you are progressing through pregnancy safely.

We’ll walk you through everything you need to know about pregnancy ultrasounds, from how often you’ll have them to whether there are any risks to getting them.

Ultrasounds use high-frequency sound waves to create a picture, called a sonogram, of the inside of your body.

During a pregnancy ultrasound, your doctor places a handheld device called a transducer either on your abdomen or inside your vagina. This sends out sound waves that travel through your body and bounce off your baby’s tissues, bones, and the surrounding fluid.

A computer then translates these returning sound waves into black-and-white images, which you’ll see on a monitor. 1

What do doctors use ultrasounds for?

While ultrasounds give you the chance to gush over your little bundle of joy, they’re also essential for monitoring your baby’s health.

Your doctor will use them to confirm your pregnancy and to: 1

• Check your baby’s heartbeat: Early in pregnancy, these images confirm that your baby’s heart has started beating, which you’ll often be able to hear yourself. This will also give you much-needed peace of mind, as the risk of all types of miscarriage drops once your doctor detects a heartbeat.
• Confirm the location of your pregnancy: Your doctor will also use these early ultrasounds to check that your baby has implanted inside your uterus correctly. Ultrasounds are especially important for detecting an ectopic pregnancy (a dangerous condition where your baby implants outside of your uterus, often in the fallopian tube).
• Track your baby’s growth: Doctors use ultrasounds to check that a baby is growing as expected and that their anatomy is developing normally. They’ll also use this ultrasound to calculate your due date based on your baby’s size, which is the most accurate way to find out when she will make her debut.

Many expectant parents also get another exciting piece of news from a second-trimester ultrasound: your doctor may be able to tell you your baby’s sex (if you want to find out, that is).

How soon can you see your baby on an ultrasound?

If you, like most parents-to-be, are desperate to catch that first glimpse of your baby in the womb, you’ll be glad to hear that you can often see your baby as early as week 6 of your pregnancy, even though she’ll still be quite small at that point (just about the size of a sweet pea). 1

If your pregnancy is progressing as expected, you’ll usually only need to have two ultrasounds: one in the first trimester and another in the second.

Here’s the rough schedule of your ultrasounds during pregnancy based on which trimester you’re in:

First-trimester scan

You’ll usually have your first ultrasound between week 6 and week 9 of your pregnancy, although you could get it any time before you’re 14 weeks pregnant.

During this first-trimester ultrasound, your doctor will confirm your baby’s heartbeat and establish a more refined due date than their initial estimate (from your LMP) by measuring from the top of her head to her bottom (crown-to-rump length).

They’ll also: 1

• Ensure your pregnancy is in the uterus: As mentioned, your doctor will check that your baby has implanted in your uterus, ruling out an ectopic pregnancy.
• Determine the number of babies: Your sonographer will also use this ultrasound to check for signs that you’re carrying twins or multiples, as you’ll generally have more than one gestational sac if you’re carrying multiple babies.
• Examine your reproductive organs: Your sonographer will also look at your uterus, ovaries, and cervix to check for any issues.

Mid-pregnancy anatomy scan

During your second trimester (around week 18 to week 22 of pregnancy), your doctor will use the detailed anatomy scan to get a comprehensive look at your baby’s development from head to toe.

As mentioned, this ultrasound is often when many parents-to-be learn their baby’s sex, and many prospective parents even (incorrectly) call it the “gender scan.” If you’d like to find out, your sonographer can look for differences in your baby’s gender scan to gauge whether you’re expecting a boy or a girl.

During this appointment, your sonographer will also: 2

• Measure your baby’s size: Measurements of the head, abdomen, and thigh bone are taken to ensure your baby is growing at the expected rate.
• Examine your baby’s major organs: Your sonographer will check the development of your baby’s brain, heart, spine, stomach, and other vital organs for any structural abnormalities.
• Screen your baby for birth defects: This scan helps your doctor detect signs of certain conditions, such as neural tube defects, a cleft palate, and congenital heart issues.
• Check your amniotic fluid: Your doctor will check your level of amniotic fluid (the liquid that surrounds your baby in the amniotic sac).
• Verify your placenta’s location: Your sonographer will also ensure that your placenta isn’t covering your cervix (a condition known as placenta previa), which can cause complications for you and your baby.

Ultrasounds in the third trimester

In a low-risk pregnancy, you won’t usually need a third-trimester ultrasound. However, your doctor may order one if they suspect there’s an issue that they need to address, something we’ll elaborate on below.

While most pregnant women only really need two ultrasounds, depending on your circumstances, your doctor may order more scans throughout your pregnancy.

Conditions that may make a third-trimester ultrasound necessary

Your doctor may order a later-pregnancy ultrasound if they believe they need to:

• Closely monitor your baby’s growth, especially if they’re concerned she’s too large or too small
• Check that she’s in a “head-down” position for birth and that something isn’t causing your baby to be in the breech position (feet-down)
• Reassess your placenta’s location

Conditions that require more ultrasounds throughout pregnancy

Your doctor may also order more frequent ultrasounds throughout your entire pregnancy if: 1

• A previous test detected a potential problem
• You’re carrying multiples
• You experience bleeding or spotting during your pregnancy, such as from a subchorionic hemorrhage (where you have bleeding between your uterine wall and your baby’s amniotic sac)
• Your doctor needs to perform an amniocentesis (taking a sample of your amniotic fluid)
• Your doctor thinks you’re at risk of preterm labor

They’ll only ever perform more ultrasounds if it’s medically necessary or you have a higher risk of complications during your pregnancy (e.g., if you have diabetes).

You usually won’t need to make special preparations before an ultrasound, though your doctor might give you specific instructions depending on how far along you are.

Before the procedure, you may need to change into a hospital gown. This tends to be more common for abdominal ultrasounds than transvaginal ultrasounds.

If you like, you can bring a partner or someone else to support you, although if you have other kids, think carefully before having them in the room, as you and your sonographer will need to be focused throughout the procedure. 1

Whether you’re having an abdominal or transvaginal ultrasound, it will be a minor procedure. Ultrasounds usually aren’t painful and last around 30 minutes or less. 1

You can watch the screen during the procedure, but don’t be offended if the technician (sonographer) is quiet and focused and refrains from chatting too much about what you’re seeing. Their role is to capture high-quality images and measurements.

They’re trained to perform the exam, but a radiologist or your doctor is the one who will interpret the results and explain them to you.

In more detail, here’s what you can expect from both types of ultrasound, abdominal and transvaginal: 3

Abdominal ultrasound

This is the most common type of pregnancy ultrasound. The steps are as follows:

1. You’ll lie back on the examination table and expose your belly
2. Your technician will apply a special water-based gel to your skin, which will help the sound waves travel from the transducer to your body.
3. They’ll then glide the transducer across your abdomen, applying gentle pressure to capture images from different angles.

Transvaginal ultrasound

Your doctor may opt for a transvaginal ultrasound earlier on in your pregnancy because it will provide them with a clearer and more detailed picture of your baby and reproductive organs.

Here are the steps for transvaginal ultrasounds:

1. You’ll need to undress from the waist down and lie on an exam table, often with your feet in stirrups.
2. Your sonographer will cover a small, thin ultrasound probe with a sterile sheath and lubricant.
3. They’ll gently insert the probe a few inches into your vagina. You may feel some pressure, but the procedure shouldn’t be painful.

After finishing your ultrasound, a radiologist or your doctor will review the images. They’ll then discuss the results with you.

Your doctor will generally schedule a follow-up appointment with you the next day, so you can go over the results together. 1

Are ultrasounds ever inaccurate?

While ultrasounds are generally very accurate and provide valuable information, they aren’t perfect.

For example, an ultrasound can provide a good estimate of your baby’s size and weight, but this is not always exact. The estimate may be over or under your baby’s actual birth weight, especially if you get the ultrasound when you’re further along in your pregnancy. 4

When it comes to calculating your due date, an ultrasound can, once again, only give you an estimate. In fact, only about 5% of babies are actually born on their estimated due dates. 5

Standard two-dimensional (2D) imaging is used for most prenatal screenings. However, your doctor may also use other, more advanced types of ultrasounds for specific situations.

Other common types of ultrasounds include: 6

• 3D ultrasounds: These compile multiple 2D images to create a three-dimensional still picture of your baby. This gives your doctor a better look if they spot a potential abnormality, like a cleft lip.
• 4D ultrasounds: With a 4D ultrasound, your doctor will create a live video of your baby moving in 3D. You can see your baby yawn, stretch, or suck their thumb in real-time.
• Fetal echocardiography: If a standard ultrasound suggests your baby has a potential heart issue or you have a family history of congenital heart defects, your doctor may order this specialized scan. A trained technician will use this kind of ultrasound to create a detailed image of your baby’s heart structure.

Regular 3D and 4D ultrasounds are safe for pregnant women and have been used in prenatal care for over two decades.

Unlike X-rays, which use radiation, ultrasounds use sound waves to create an image.

Most major medical organizations, including the American College of Obstetricians and Gynecologists (ACOG), agree that ultrasounds are safe for both you and your baby as long as they’re performed for a medical reason by a qualified professional. 7

Is getting too many ultrasounds bad for your baby?

Although medical ultrasounds are generally safe, too many ultrasounds could potentially have long-term effects on your baby.

Ultrasound waves expose your baby to heat, which, in some cases, can theoretically lead to birth defects. With that in mind, doctors adhere to the ARALA principle, or “as low as reasonably achievable.”

This means they’ll limit the use of ultrasounds when unnecessary and try to use the lowest settings on the machines, which will expose your baby to the lowest amount of energy possible. 6

Are elective ultrasounds safe?

Considering that doctors avoid unnecessary ultrasounds, you should be cautious about “elective ultrasounds,” also known as non-medical ultrasounds.

Some parents opt for these to create “keepsake” images of their developing babies, but both ACOG and the US Food and Drug Administration (FDA) discourage the use of ultrasounds for non-medical purposes. 7 8

Not only do these elective ultrasounds expose your baby to potentially dangerous heat energy, but most of the clinics that offer elective ultrasounds aren’t run by medical professionals. The ultrasound technicians at these clinics aren’t necessarily trained to spot issues in your baby, so you could miss a problem that needs to be dealt with quickly. 9

For these reasons, it’s best to stick to scans that are medically necessary and performed by certified and trained technicians.

Pregnancy ultrasounds are more than just a chance to get a sneak peek at your growing baby. Your doctor will use the information from your ultrasounds to check that she’s developing as expected, catch issues early on, and ensure that your body is adjusting to pregnancy well.

Again, as tempting as it may be to get an extra few snaps of your baby, you should only opt for ultrasounds that are performed by trained medical professionals.