Ultrasound in Pregnancy

Overview

What is an ultrasound in pregnancy?

A prenatal ultrasound (or sonogram) is a test during pregnancy that checks on the health and development of your baby. An obstetrician, nurse midwife or ultrasound technician (sonographer) performs ultrasounds during pregnancy for many reasons. Sometimes ultrasounds occur to check on your baby and make sure they’re growing properly. Other times your pregnancy care provider orders an ultrasound after they detect a problem.

During an ultrasound, sound waves are sent through your abdomen or vagina by a device called a transducer. The sound waves bounce off structures inside your body, including your baby and your reproductive organs. Then, the sound waves transform into images that your provider can see on a screen. It doesn’t use radiation, like X-rays, to see your baby.

Even though prenatal ultrasounds are safe, you should only have them when it’s medically necessary. If there’s no reason for an ultrasound (for example, if you just want to see your baby), your insurance company might not pay for it.

Prenatal ultrasounds may be called fetal ultrasounds or pregnancy ultrasounds. Your provider will talk to you about when you can expect ultrasounds during pregnancy based on your health history.

Why is a fetal ultrasound important during pregnancy?

An ultrasound is one of the few ways your pregnancy care provider can see and hear your baby. It can help them determine how far along you are in pregnancy, if your baby is growing properly or if there are any potential problems with the pregnancy. Ultrasounds may occur at any time in pregnancy depending on what your provider is looking for.

What can be detected in a pregnancy ultrasound?

A prenatal ultrasound does two things:

  • Evaluates the overall health, growth and development of the fetus.
  • Detects certain complications and medical conditions related to pregnancy.

In most pregnancies, ultrasounds are positive experiences and pregnancy care providers don’t find any problems. However, there are times this isn’t the case and your provider detects birth disorders or other problems with the pregnancy.

Reasons why your provider performs a prenatal ultrasound are to:

Ultrasound is also an important tool to help providers screen for congenital conditions (conditions your baby is born with). A screening is a type of test that determines if your baby is more likely to have a specific health condition. Your provider also uses ultrasound to guide the needle during certain diagnostic procedures in pregnancy like amniocentesis or CVS (chorionic villus sampling).

An ultrasound is also part of a biophysical profile (BPP), a test that combines ultrasound with a nonstress test to evaluate if your baby is getting enough oxygen.

How many ultrasounds do you have during your pregnancy?

Most pregnant people have one or two ultrasounds during pregnancy. However, the number and timing vary depending on your pregnancy care provider and if you have any health conditions. If your pregnancy is high risk or if your provider suspects you or your baby has a health condition, they may suggest more frequent ultrasounds.

When do you have your first prenatal ultrasound?

The timing of your first ultrasound varies depending on your provider. Some people have an early ultrasound (also called a first-trimester ultrasound or dating ultrasound). This can happen as early as seven to eight weeks of pregnancy. Providers do an early ultrasound through your vagina (transvaginal ultrasound). Early ultrasounds do the following:

  • Confirm pregnancy (by detecting a heartbeat).
  • Check for multiple fetuses.
  • Measure the size of the fetus.
  • Help confirm gestational age and due date.

Some providers perform your first ultrasound closer to 12 weeks of pregnancy.

20-week ultrasound (anatomy scan)

You can expect an ultrasound around 18 to 20 weeks in pregnancy. This is known as the anatomy ultrasound or 20-week ultrasound. During this ultrasound, your pregnancy care provider can see your baby’s sex (if your baby is in a good position for viewing their genitals), detect birth disorders like cleft palate or find serious conditions related to your baby’s brain, heart, bones or kidneys. If your pregnancy is progressing well and with no complications, your 20-week ultrasound may be your last ultrasound during pregnancy. However, if your provider detects a problem during your 20-week ultrasound, they may order additional ultrasounds.

How soon can you see a baby on an ultrasound?

Pregnancy care providers can detect an embryo on an ultrasound as early as six weeks into the pregnancy. An embryo develops into a fetus around the eighth week of pregnancy.

If your last menstrual period isn’t accurate, it’s possible that it may be too early to detect a fetal heart rate.

Which ultrasound is most important during pregnancy?

All ultrasounds during pregnancy are important. Your pregnancy care provider uses ultrasound to tell them important information about your pregnancy.

Test Details

What are the two main types of pregnancy ultrasounds?

The two main types of pregnancy ultrasound are transvaginal ultrasound and abdominal ultrasound. Both use the same technology to produce images of your baby. Your pregnancy care provider performs a transvaginal ultrasound by placing a wand-like device inside your vagina. They perform an abdominal ultrasound by placing a device on the skin of your belly.

Transvaginal ultrasound

During a transvaginal ultrasound, your pregnancy care provider places a device inside your vaginal canal (similar to how you place a tampon). In early pregnancy, this ultrasound helps to detect a fetal heartbeat or determine how far along you are in your pregnancy (gestational age). Images from a transvaginal ultrasound are clearer in early pregnancy as compared to abdominal ultrasound.

Abdominal ultrasound

Your pregnancy care provider performs an abdominal ultrasound by placing a transducer directly on your skin. Then, they move the transducer around your belly (abdomen) to capture images of your baby. Sometimes slight pressure has to be applied to get the best views. Providers use abdominal ultrasounds after about 12 weeks of pregnancy.

Traditional ultrasounds are 2D. More advanced technologies like 3D or 4D ultrasound can create better images. This is helpful when your provider needs to see your baby’s face or organs in greater detail. Not all providers have 3D or 4D ultrasound equipment or specialized training to conduct this type of ultrasound.

Your provider may recommend other types of ultrasounds. Examples of additional ultrasounds are:

  • Doppler ultrasound: This type of ultrasound checks how your baby’s blood flows through its blood vessels. Most Doppler ultrasounds occur later in pregnancy.
  • Fetal echocardiogram: This type of ultrasound looks at your baby’s heart size, shape, function and structure. Your provider may use it if they suspect your baby has a congenital heart condition, if you had another child that had a heart condition or if you have certain health conditions that warrant taking a closer look at the heart.

How do I prepare for the test?

There’s no special preparation for an ultrasound. Some pregnancy care providers ask that you come with a full bladder and don’t use the restroom before the test. This helps them view your baby better on the ultrasound. You can bring a support person, but bringing children is discouraged as this is an important test that requires complete focus.

You may be asked to change into a hospital gown, but this isn’t usually required for abdominal ultrasounds. If your provider is performing a transvaginal ultrasound in your first trimester, you’ll put on a hospital gown or undress from the waist down.

What should I expect during a prenatal ultrasound?

You’ll lie on a padded examining table during the test. Most ultrasounds occur in a dimly lit room, which helps your ultrasound technician (or sonographer) see the screen. Your sonographer applies a small amount of water-soluble gel to the skin of your belly. The gel doesn’t harm your skin or stain your clothes, but it may feel cold. This gel helps transmit sound waves more efficiently.

Next, the sonographer places a transducer on the skin of your abdomen. The transducer sends sound waves into your body, which reflect off internal structures, including your baby. The sound waves that reflect back create pictures on a screen. Your sonographer uses these images to take important measurements such as your baby’s head circumference and length. You may see them making lines on the screen or clicking a button to “freeze” certain angles.

There’s virtually no discomfort during a prenatal ultrasound. You may feel mild discomfort if you have to pee. The ultrasound test takes about 30 minutes to complete.

If you have a transvaginal ultrasound, the process is only different in that the transducer is inside your vagina and not on your belly.

What should I expect after a pregnancy ultrasound?

If you had an abdominal ultrasound, your sonographer wipes the gel off your belly. They may print off some ultrasound pictures for you to take home with you.

In most cases, your sonographer won’t discuss the results of your test with you. If your obstetrician performs your ultrasound, they may discuss what they see as they go along.

If a sonographer performs your ultrasound, an obstetrician will look at the images, then discuss their findings with you at your next appointment. Most practices schedule your appointment right after your ultrasound so you get your results the same day.

What are the risks of prenatal ultrasounds?

Studies have shown ultrasounds are safe during pregnancy. There are no harmful side effects to you or your baby.

Is it safe to do an ultrasound every month during pregnancy?

While ultrasounds are safe for you and your baby, most major medical associations recommend that pregnancy care providers should only do ultrasounds when the tests are medically necessary. If your ultrasounds are normal and your pregnancy is uncomplicated or low risk, repeat ultrasounds aren’t necessary.

Results and Follow-Up

What results do you get on a pregnancy ultrasound?

Your ultrasound results will be normal or abnormal. A normal result means your pregnancy care provider didn’t find any problems and that your baby is growing and developing normally. An abnormal result means your provider noticed something irregular. If they do, your provider will order additional ultrasounds or diagnostic tests to determine if something is wrong.

Occasionally, the ultrasound is incomplete if there’s difficulty seeing all the structures needed for that particular ultrasound. Your baby’s position or movement sometimes makes it difficult to see everything your provider needs to see. If this is the case, you’ll need a repeat ultrasound and they’ll try again.

There are some limitations to ultrasounds, so your provider may not find certain abnormalities until after birth.

What are reasons you need more ultrasounds during pregnancy?

There are several reasons your pregnancy care provider may order additional ultrasounds during your pregnancy. Some of these reasons include:

  • Problems with your ovaries, uterus, cervix or other pelvic organs.
  • Your baby is measuring small for their gestational age or your provider suspects IUGR (intrauterine growth restriction).
  • Problems with the placenta like placenta previa or placental abruption.
  • You’re pregnant with twins, triplets or more.
  • Your baby is breech.
  • You have too much amniotic fluid (polyhydramnios).
  • You have too little amniotic fluid (oligohydramnios).
  • You have a condition like gestational diabetes or preeclampsia.
  • Your baby has a congenital disorder.

Normal results on pregnancy ultrasounds can vary. Generally, a normal result means your baby appears healthy and your provider didn’t find any issues.

Why do some pregnancy providers schedule ultrasounds differently?

The number of ultrasounds you’ll have and when you have them can vary between providers. Every practice operates differently and some providers do things differently based on your health history or symptoms.

When does a pregnancy ultrasound determine sex?

Your baby’s sex isn’t visible on an ultrasound until about 18 to 20 weeks. Be sure to tell your pregnancy care provider whether or not you want to know the sex of your baby before your ultrasound.

A note from Cleveland Clinic

An ultrasound during pregnancy can be both exciting and terrifying. Your pregnancy care provider uses ultrasound to get a better idea of how your baby is growing and developing. There are different types of ultrasounds, and the exact timing may vary depending on your provider. Most pregnant people have two ultrasounds — one in the first trimester and one in the second trimester. However, if there’s a potential complication or medical reason for more ultrasounds, your provider will order more as a precaution. Talk to your provider about the ultrasound schedule during pregnancy and what you can expect.

Last reviewed by a Cleveland Clinic medical professional on 09/28/2022.

References

  • American Pregnancy Association. Ultrasound Sonogram. (https://americanpregnancy.org/healthy-pregnancy/pregnancy-health-wellness/ultrasound/) Accessed 9/28/2022.
  • March of Dimes. Ultrasound during pregnancy. (https://www.marchofdimes.org/pregnancy/ultrasound-during-pregnancy.aspx) Accessed 9/28/2022.
  • National Health Service. Ultrasound scans in pregnancy. (https://www.nhs.uk/pregnancy/your-pregnancy-care/ultrasound-scans/) Accessed 9/28/2022.
  • Ulrich CC, Dewald O. Pregnancy Ultrasound Evaluation. (https://www.ncbi.nlm.nih.gov/books/NBK557572/) 2022 May 2. In: StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2022 Jan-. Accessed 9/28/2022.

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