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.
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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:
- Confirm you’re pregnant.
- Check for ectopic pregnancy, molar pregnancy, miscarriage or other early pregnancy complications.
- Determine your baby’s gestational age and due date.
- Check your baby’s growth, movement and heart rate.
- Look for multiple babies (twins, triplets or more).
- Examine your pelvic organs like your uterus, ovaries and cervix.
- Examine how much amniotic fluid you have.
- Check the location of the placenta.
- Check your baby’s position in your uterus.
- Detect problems with your baby’s organs, muscles or bones.
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.
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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.