Pregnancy Ultrasounds: What to Expect at Every Stage

You’ve seen the two pink lines and started navigating the ups and downs of early pregnancy. But for many moms-to-be, it doesn’t truly feel real until that first ultrasound. An ultrasound is a routine prenatal test that lets your provider see how your baby is developing and is the first peek at the little life growing inside you.

Most pregnancies include two-three routine ultrasounds, but the exact number can depend on your health history, how the pregnancy is progressing and what your provider needs to check along the way.

Ultrasounds are a normal, safe and routine part of prenatal care. They use sound waves rather than radiation to help your care team make sure everything is on track.

Michael Leonardi, MD, maternal fetal specialist, shares more about ultrasound milestones in each trimester, so you know why it’s done and what your provider is looking for.

First Trimester Ultrasounds

For most moms, the first ultrasound happens during the first trimester, usually around six-eight weeks. Some people have an earlier or later ultrasound if they have symptoms, have a history of irregular menstrual cycles, have used fertility care or need closer monitoring.

At this stage, the type of ultrasound you receive will depend on how far along you are in your pregnancy. Your provider will typically start with an abdominal ultrasound, which is performed over the abdomen using a handheld device that glides across your skin with gel. If you are earlier in your pregnancy, your provider may perform a transvaginal ultrasound, where a probe will be gently placed in your vagina to get a clearer view of your baby, who will still be very small.

At this ultrasound, you’ll be able to hear your baby’s heartbeat, see their head and body, and sometimes even tiny arms and legs.

Your provider will measure your baby’s length from their head to their rump, called crown-rump length, to help determine their gestational age as well as provide a more accurate due date. They will also listen to your baby’s heart rate as well as measure the gestational sac, a fluid-filled sac that surrounds the embryo.

Your provider may also measure a small pocket of fluid at the back of your baby’s neck to help assess the risk of certain chromosomal conditions, such as Down syndrome. This is called a nuchal translucency (NT) measurement. This ultrasound typically takes about 20-30 minutes.

Second Trimester Ultrasounds

By the second trimester, your baby has grown tremendously and so have the details your provider can see on an ultrasound. This is when you’ll likely have the anatomy scan, the most detailed routine ultrasound of pregnancy and one of the biggest milestones for many expecting parents.

20-Week Anatomy Scan

Usually performed between 18 and 22 weeks, the anatomy scan ultrasound is a detailed, head-to-toe check of your baby’s growth and development. For most moms, this ultrasound will be done over your abdomen, allowing the care team to assess your baby in real time. Some women may receive a transvaginal ultrasound to measure the length of your cervix, which can help identify if you are at an increased risk for early delivery.

During this ultrasound, your provider will carefully examine your baby’s:

• Brain and face
• Heart and major blood vessels
• Spine
• Kidneys, stomach and other organs
• Arms, legs, hands and feet

They’ll also check the location of the placenta, measure the amount of amniotic fluid in your belly and make sure your baby is growing as expected. If you’re planning to find out the gender of your baby, this is often the ultrasound that reveals it – provided your baby cooperates.

The 20-week anatomy scan typically takes a little longer to complete, about 30-60 minutes.

“The anatomy scan is about much more than seeing your baby,” said Dr. Leonardi. “It’s one of the most important ultrasounds because it allows us to carefully evaluate your baby’s development. If we notice something that needs a closer look, we can connect you with a maternal-fetal medicine specialist early so you have the right care and support throughout your pregnancy.”

Third Trimester Ultrasounds

For many moms, the anatomy scan is the last routine ultrasound of pregnancy. If your pregnancy is progressing normally, you may not need another scan before your baby arrives. However, some women have additional ultrasounds in the third trimester, often at around 32 weeks, to monitor their baby’s growth, check the location of the placenta or measure amniotic fluid levels. If you have a high-risk pregnancy, it’s also common to have more frequent ultrasounds during this stage.

Are ultrasounds safe for mom and baby?

Prenatal ultrasounds are considered safe and have been used for decades as a routine part of pregnancy care.

Unlike X-rays or CT scans, ultrasounds do not use radiation. Instead, they use high-frequency sound waves to create images of your baby.

Your care team will recommend ultrasounds when they’re medically appropriate, whether that’s for a routine pregnancy milestone or to keep a closer eye on you or your baby. Ultrasounds are most valuable when they’re performed for a medical reason and interpreted by trained professionals.

3D and 4D Ultrasounds

3D and 4D ultrasound are special types of imaging that provide more detailed, lifelike views of your baby compared to standard imaging. 3D ultrasound creates still, three-dimensional images of your baby, while 4D ultrasound shows real-time movement, such as facial expressions or small movements in the womb.

In everyday prenatal care, providers primarily use standard 2D ultrasounds for medical monitoring. 4D ultrasound technology is not typically part of routine pregnancy care, but it may sometimes be used in certain specialty or high-risk settings when additional detail or evaluation is helpful.

3D and 4D ultrasounds are also offered through boutique or keepsake imaging centers, where the focus is on bonding and baby pictures rather than medical assessment.

Why Ultrasounds Matter

While it’s easy to think of ultrasounds as just a chance to see your baby, they actually play an important role in your overall pregnancy care.

Ultrasounds help your care team:

• Track your baby’s growth and development
• Identify potential concerns early
• Monitor placenta position and amniotic fluid levels
• Plan for the safest possible delivery

Sometimes an ultrasound may identify something that means your baby could benefit from extra support at birth. When that happens, it allows your care team to plan ahead so that, if needed, delivery can take place in a hospital with specialized newborn care team ready to support your baby right away.

“Ultrasounds are an essential part of prenatal care, especially for high-risk pregnancies,” said Dr. Leonardi. “For routine pregnancies, when something does come up, it gives us time to plan ahead so we can ensure the safest possible delivery and the right level of care for both mom and baby, including access to specialized newborn support if needed.”