Most pregnant women have two to three ultrasounds over the course of a full pregnancy, though the official minimum recommendation is just one. The American College of Obstetricians and Gynecologists (ACOG) says every pregnant woman should have at least one standard ultrasound, typically performed between 18 and 22 weeks. In practice, though, most providers also offer an early scan in the first trimester, and some pregnancies require additional monitoring later on.
The First Trimester Scan (10 to 14 Weeks)
A first trimester ultrasound isn’t technically required for every pregnancy, but it’s offered routinely by most OB practices. This early scan, sometimes called a dating scan, usually happens between 10 and 14 weeks. Its main job is to confirm the pregnancy is in the uterus, check for a heartbeat, determine whether you’re carrying multiples, and establish a due date based on the baby’s size. If you’ve had irregular periods or aren’t sure when you conceived, this scan is especially useful for pinning down gestational age.
At this stage, the baby is still very small, so providers often use a transvaginal ultrasound (a slim probe placed inside the vagina) rather than the familiar wand-on-the-belly approach. Before about 11 weeks, a transvaginal scan produces a much clearer picture. After 11 or 12 weeks, most scans switch to the abdominal approach. You can decline a transvaginal scan and request an abdominal one instead, but the image quality in early pregnancy will be lower, which could delay or complicate any findings.
If you opt into genetic screening, the same visit may include a nuchal translucency measurement. This checks the thickness of a fluid-filled space at the back of the baby’s neck, which, combined with a blood test, helps estimate the likelihood of Down syndrome and certain other chromosomal conditions. This screening needs to happen before 14 weeks to be accurate.
The Anatomy Scan (18 to 22 Weeks)
The mid-pregnancy anatomy scan is the one ultrasound virtually every pregnant person gets. Scheduled between 18 and 22 weeks, it’s the most thorough look at your baby before delivery. A sonographer will systematically photograph and measure dozens of structures: the heart, brain, spine, kidneys, bladder, stomach, intestines, chest, lungs, arms, legs, hands, feet, fingers, toes, lips, chin, nose, and eyes. They’ll also record the heart rate.
Beyond the baby itself, the sonographer checks several things about the pregnancy environment. They’ll look at blood flow through the umbilical cord and where it attaches to the placenta, note the placenta’s position (important for delivery planning), measure the amount of amniotic fluid, and examine your uterus, ovaries, and cervix. If you want to learn the baby’s sex, this is typically the appointment where that’s possible.
The anatomy scan usually takes 30 to 45 minutes, sometimes longer if the baby is in an awkward position. If the sonographer can’t get a clear view of a particular structure, you may be asked to come back for a follow-up scan a week or two later. That’s common and not necessarily a sign that something is wrong.
When You Might Need More Scans
A low-risk pregnancy with no complications may only involve those two ultrasounds. But plenty of situations call for additional imaging in the second or third trimester. Growth scans, usually performed after 28 weeks, track the baby’s size over time and are common if your provider suspects the baby is measuring unusually large or small, if you have gestational diabetes, high blood pressure, or are carrying twins or more.
Some women end up having a biophysical profile, or BPP, in the third trimester. This is a specialized ultrasound that scores five aspects of fetal well-being: heart rate, breathing movements, body movements, muscle tone, and amniotic fluid levels. Each category gets a score of 0 or 2, for a total possible score of 10. A score of 8 to 10 is reassuring. A score of 6 is considered uncertain and typically leads to a repeat test within 12 to 24 hours. A score of 4 or below usually means the baby needs to be delivered soon. Low amniotic fluid on its own, regardless of the total score, triggers closer monitoring.
Other reasons you might have extra ultrasounds include bleeding at any stage, a history of preterm birth, concerns about cervical length, or a placenta that’s positioned over or near the cervix (placenta previa). Some high-risk pregnancies involve ultrasounds every few weeks in the final trimester.
What a Typical Count Looks Like
For a straightforward, low-risk pregnancy: expect two ultrasounds. One around 10 to 14 weeks, one around 18 to 22 weeks. If your provider skips the early scan and you have no complications, you may have just one. If any risk factors develop, the number can climb to five, six, or more. There’s no single “correct” number. The count depends entirely on what’s happening in your specific pregnancy.
Are Extra Ultrasounds Safe?
Diagnostic ultrasound has been used in pregnancy for decades with no confirmed harmful effects. It doesn’t use radiation. It works by sending sound waves into the body and reading the echoes that bounce back. That said, ultrasound does deposit small amounts of energy into tissue, which is why medical organizations follow something called the ALARA principle: keep exposure “as low as reasonably achievable.” Sonographers are trained to use the lowest power settings needed and keep scan times as short as possible while still getting the information they need.
The American Institute of Ultrasound in Medicine specifically recommends keeping the thermal index (a measure of tissue heating) at or below 0.7 when checking fetal heart activity. Pulsed Doppler ultrasound, which measures blood flow and uses higher acoustic output, is not recommended as a routine tool and is reserved for situations where there’s a clinical reason to use it.
One area where medical organizations draw a firm line is “keepsake” ultrasounds at commercial studios. The AIUM calls the use of ultrasound without a medical indication “inappropriate and contrary to responsible medical practice.” These freestanding imaging businesses often operate without physician oversight and with no regulation of staff training. Getting photos or video clips during a medically indicated scan is perfectly fine, but scheduling extra sessions purely for entertainment purposes is discouraged by every major obstetric organization.