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Pregnancy Ultrasounds: What to Expect When You’re Expecting

Their first heartbeat. That first glimpse of your tiny little baby inside of you. Next to delivering your bundle of joy, your first prenatal ultrasound is one of the most exciting moments a parent will experience.

Ultrasounds are a regular part of prenatal medical care for most pregnant women, but it’s not just about getting your child’s first set of black-and-white pics to put on your fridge or share on social media. There are also a number of important medical reasons your doctor and medical team need them.

But how many ultrasounds should you have, are they safe and when should you have them? Here’s what you need to know when you are expecting.

What are prenatal ultrasounds?

A prenatal ultrasound scan uses sound waves to make images that show your baby’s shape and position. The way this happens is that the sound waves actually bounce off the baby’s bones and tissues and send signals back to the machine that converts them into images of your baby.

Pretty cool, right? And since it uses sound waves and not radiation, prenatal scans are safe when performed by your healthcare provider.

How is an ultrasound scan performed?

When it comes to prenatal ultrasounds, there are two ways of performing them: transvaginal or abdominally.

Transvaginal ultrasounds use a small elongated looking wand called a transducer that is inserted into your cervix. This wand painlessly emits sound waves to obtain images.

“They are typically used during the first trimester for size and dates, although some doctors may request if the mother is bleeding to rule out a miscarriage or to find a heartbeat to rule out fetal death,” said Pamela Garrison, a registered diagnostic medical sonographer and associate manager at Banner Imaging Services. “Sometimes we do a transvaginal ultrasound late in the pregnancy during the third trimester to check the cervical length or the position of the placenta (how close it is to the cervix), if it was low-lying or covering during previous ultrasounds.”

Abdominal ultrasounds are performed on your belly using gel and a transducer to create the image of your baby. If this type of ultrasound is performed, it’s usually recommended that you wear something where you can easily lift your shirt.

In special cases, your doctor may also use other kinds of ultrasounds to get more information on your baby. These include doppler ultrasounds and 3D and 4D ultrasounds.

How many ultrasounds will I have during pregnancy?

While there is no official recommendation, typically ultrasounds are performed during the first trimester and the second trimester.

“Ultrasounds are typically done during the first trimester between 6 to 12 weeks to confirm your pregnancy and for size and dates and during the second trimester between 18 to 24 weeks where you learn your baby’s sex if you like,” said Garrison. “However, sometimes a third trimester scan may be necessary if the the fetus is too big or too small for dates, fluid is too low, the position is needed, or the patient is high risk either due to multiple gestations, maternal age or a concern found during previous ultrasounds.”

You may also have an ultrasound as part of a genetic test, such as a nuchal translucency, or at any other time if there are signs of a problem with your baby or if you have diabetes, hypertension or other medical complications.

If you are unsure how many you need, don’t hesitate to talk to your provider.

What are the reasons for having an ultrasound?

Ultrasounds are important during pregnancy to see if the mother is carrying more than one fetus, rule out any fetal anomalies and check the size and dates of the fetus to ensure correct growth,” Garrison said. “We check the amniotic fluid to make sure the fetus has enough—not too little (oligohydramnios) or too much (polyhydramnios). We also use them to check the placenta and the cervix.”

Ultrasounds may be performed at various times throughout your pregnancy for different reasons, but typically this is what your doctor will look for during each trimester.

In the first trimester:
  • Establish dates of pregnancy
  • Confirm fetal heartbeat
  • Determine the number of fetuses and placental structures
  • Diagnose ectopic pregnancy or miscarriage
In the second trimester:
  • Confirm or establish dates of pregnancy (if it wasn’t done in first trimester)
  • Examine baby’s anatomy for abnormalities
  • Examine blood flow patterns
  • Observe baby’s behavior and activity
  • Determine baby’s sex, if you’d like to know
  • Monitor baby’s growth
  • Measure the length of the cervix
  • Examine the placenta
Third trimester and additional ultrasounds:

Some doctors may order additional ultrasounds during the third trimester or at any other time during your pregnancy when they feel it’s necessary.

“This may include some women who are high risk due to gestational age, have multiple gestations or if their doctor sees something during a previous ultrasound that warrants a level two ultrasound, a more in-depth scan of the fetal anatomy,” Garrison added.

What if the ultrasound shows a problem?

For most women, the ultrasound will show that the baby is growing normally and there are no other concerns. Sometimes, however, an ultrasound may show that you and your baby need additional care or treatment. In the unlikely event this occurs, your doctor will work with you to ensure you and your baby are given the best possible outcome.

What should I expect before, during and after pregnancy?

When baby is on the way, especially your first, you will likely have lots of questions. Here are some pregnancy articles you may be interested in:

Final takeaway

Pregnancy ultrasounds may be your first exciting glimpse at your baby, but they are also important during pregnancy to ensure you and baby are doing well. If you are pregnant and/or have just found out you are pregnant, make sure you discuss your prenatal care with your doctor.

To find a Banner Imaging location near you, or to make an appointment with a Banner Health specialist, visit bannerhealth.com.

Women's Health Pregnancy

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