Most pregnant women get two to three ultrasounds over the course of a standard, low-risk pregnancy. The American College of Obstetricians and Gynecologists recommends at least one, typically performed between 18 and 22 weeks. In practice, though, most providers also order an early scan in the first trimester, and some add a third depending on your specific circumstances.
If your pregnancy is considered high-risk, that number can climb significantly, sometimes to an ultrasound every two to four weeks in the third trimester alone. Here’s what to expect at each stage and why the number varies so much from person to person.
First Trimester: Confirming the Pregnancy
A first-trimester ultrasound isn’t technically required for every pregnancy, but it’s become routine at most practices. This early scan is usually done between 6 and 10 weeks and serves a few basic purposes: confirming a heartbeat, checking whether you’re carrying multiples, and measuring the fetus to establish a more accurate due date. Because the fetus is still very small, this scan is done with a transvaginal probe rather than the wand-on-the-belly approach most people picture. Transvaginal imaging produces much clearer pictures this early on. After about 12 weeks, providers switch to abdominal ultrasounds for the rest of the pregnancy.
Some women also have a screening scan between 11 and 13 weeks that measures a small pocket of fluid at the back of the baby’s neck. This measurement, called the nuchal translucency, helps estimate the risk of certain chromosomal conditions like Down syndrome. It’s optional, and your provider will typically discuss it alongside blood screening tests. Not every practice offers it, so this scan alone can account for a difference of one in your total count.
The Mid-Pregnancy Anatomy Scan
The single most important ultrasound of pregnancy happens between 18 and 22 weeks. Often called the anatomy scan or anomaly scan, this is the one your provider will almost certainly recommend regardless of how healthy your pregnancy has been. It’s a detailed, head-to-toe check of the baby’s developing body.
During this scan, the sonographer examines the baby’s bones, heart, brain, spinal cord, face, kidneys, and abdomen. They’re also checking the placenta’s position and blood flow in the uterus. The scan screens for a range of structural conditions, including spina bifida, serious heart defects, and cleft lip. It’s also where many parents first learn the baby’s sex, if they want to know.
This appointment typically takes 20 to 45 minutes because the sonographer needs to capture specific views. If the baby is in an awkward position, you may be asked to walk around and come back so the baby shifts. In some cases, you’ll be called back for a follow-up scan a week or two later if certain views weren’t clear enough the first time. That follow-up doesn’t necessarily mean something is wrong.
Third Trimester Scans Aren’t Always Routine
In a straightforward pregnancy, you may not have another ultrasound after the anatomy scan. Your provider will monitor growth through fundal height measurements (the tape-measure-on-the-belly check at each prenatal visit) and won’t order additional imaging unless something seems off.
A third-trimester ultrasound becomes more likely if your provider suspects the baby is measuring too large or too small, if the baby seems less active than usual, if the placenta was in a low position at 20 weeks, or if your pregnancy goes past 40 weeks. These growth scans focus on the baby’s size, the amount of amniotic fluid, and how well the placenta is functioning.
High-Risk Pregnancies Change the Count
If you have a condition like diabetes, high blood pressure, or a history of pregnancy complications, expect significantly more ultrasounds. Third-trimester monitoring for high-risk pregnancies typically involves growth scans every two to four weeks to track the baby’s development and amniotic fluid levels. Some practices check every two weeks, while others space scans three to four weeks apart.
Research from UT Southwestern Medical Center compared these two approaches in about 200 women with conditions that can affect fetal growth. Women who received scans every two weeks didn’t have problems identified more often than those scanned every four weeks. So more frequent doesn’t necessarily mean better, and your provider will tailor the schedule to your specific situation.
Pregnancies involving multiples, decreased fetal movement, or growth that falls outside the expected range may also trigger additional specialized tests. These are usually started between 32 and 34 weeks, though they can begin earlier for more serious concerns. Some women in these categories end up with weekly or even twice-weekly monitoring sessions toward the end of pregnancy.
What a Typical Count Looks Like
For a low-risk pregnancy, the total usually breaks down like this:
- One early scan (6 to 10 weeks) to confirm the pregnancy and set a due date
- One optional screening scan (11 to 13 weeks) to assess chromosomal risk
- One anatomy scan (18 to 22 weeks) to check the baby’s development
That puts most low-risk pregnancies at two or three ultrasounds total. High-risk pregnancies can easily reach five to ten or more, depending on what’s being monitored and how frequently.
Elective and “Keepsake” Ultrasounds
Boutique ultrasound studios offer 3D and 4D imaging sessions purely for photos and videos. These aren’t medically indicated, and organizations like the American Institute of Ultrasound in Medicine have issued statements urging that ultrasound be used only when there’s a medical reason. Diagnostic ultrasound has an excellent safety record, but the official position from medical bodies is that unnecessary exposure should be avoided on principle. The sonographers at these studios also aren’t performing diagnostic evaluations, so a keepsake session doesn’t replace any of your scheduled medical scans.
Why Your Number Might Differ From a Friend’s
The variation people notice when comparing notes is real and usually explainable. Your total depends on your provider’s practice style, your insurance coverage, whether you opt into optional screenings, and whether any concerns pop up along the way. A pregnancy that starts with bleeding in the first trimester might get an extra early scan. A baby measuring small at a routine checkup could trigger a series of growth scans in the third trimester. A completely uneventful pregnancy at a practice that follows minimal guidelines might involve just one or two.
If you’re unsure why a scan has been ordered or feel like you’re getting more (or fewer) than expected, asking your provider is reasonable. Each ultrasound should have a specific clinical purpose, whether that’s establishing a due date, screening for abnormalities, or monitoring growth in a pregnancy that needs closer attention.