Most pregnant people get two ultrasounds: one in the first trimester to date the pregnancy and one between 18 and 22 weeks to check the baby’s anatomy. That said, the only scan officially recommended for every pregnancy is the mid-pregnancy anatomy scan. Everything beyond that depends on your health, your baby’s growth, and whether any complications arise.
The Standard Two-Scan Schedule
For a low-risk, uncomplicated pregnancy, the typical ultrasound schedule looks like this:
- First trimester (around 7 to 12 weeks): A dating scan confirms how far along you are and whether there’s a heartbeat. The technician measures the baby from head to bottom (crown-rump length), which is the most accurate way to estimate a due date early on. Before about 11 weeks, this is usually done with a transvaginal probe rather than the familiar wand-on-the-belly approach, simply because the baby is too small to see well from the outside.
- Mid-pregnancy (18 to 22 weeks): The anatomy scan is the big one. This is a detailed head-to-toe check of the baby’s bones, brain, spinal cord, heart, kidneys, face, and stomach. The sonographer also evaluates your placenta’s position and the blood flow in your uterus. It screens for structural issues like heart defects, spina bifida, cleft lip, and certain chromosomal conditions. This scan typically takes 20 to 45 minutes because the technician needs clear views of each structure.
From about 12 weeks onward, scans shift to the abdominal approach, where the probe moves across your belly with a layer of gel. Most people find this more comfortable than the transvaginal method used in early pregnancy.
Why Some People Get More Scans
Two scans is the baseline, not the ceiling. Your provider may add ultrasounds at several points if your pregnancy carries extra risk. Common reasons include high blood pressure, diabetes, a history of pregnancy complications, a baby measuring smaller or larger than expected, or problems with amniotic fluid levels. When a growth issue is suspected, ultrasound is the primary tool for tracking it.
A third-trimester growth scan isn’t routine for low-risk pregnancies, but research suggests it catches problems that physical exams miss. One large study found that when a universal third-trimester scan was offered instead of scanning only when something seemed off, the rate of identified growth or fluid abnormalities jumped from 7.1% to 22.2%. That means roughly one in seven additional cases were caught that would have gone unnoticed. In standard practice, though, a third-trimester scan is typically ordered only when there’s a mismatch between your belly measurements and how far along you are.
Twin and Multiple Pregnancies
Carrying twins or more means significantly more ultrasounds. The schedule depends on whether the babies share a placenta, because shared-placenta twins face higher risks of uneven blood flow and growth differences.
For twins with separate placentas (dichorionic), scans happen every four weeks starting around 24 weeks, shifting to every two weeks at 28 weeks, then weekly from 36 weeks until delivery. Twins who share a placenta but have separate sacs (monochorionic-diamniotic) need closer monitoring: every two weeks starting at 16 weeks, with growth checks every four weeks layered in. Twins who share both a placenta and a sac (monochorionic-monoamniotic, the rarest type) follow a similar biweekly schedule but often require daily monitoring with an inpatient hospital stay starting between 24 and 28 weeks.
Late-Pregnancy Monitoring Scans
If your pregnancy extends past your due date or your provider has concerns about the baby’s well-being, you may get a specialized scan called a biophysical profile. This checks five things at once: heart rate, breathing movements, body movements, muscle tone, and the amount of amniotic fluid surrounding the baby. Each area receives a score, and the total guides your care team’s decisions.
Biophysical profiles are typically done weekly, though some situations call for twice-weekly testing. If the score falls in an uncertain range, you’ll usually be rescanned within 12 to 24 hours, or your provider may recommend delivery depending on how far along you are.
Elective and “Keepsake” Ultrasounds
Boutique ultrasound studios offer 3D and 4D images or videos of your baby as souvenirs. While getting a keepsake photo during a medically necessary scan is perfectly fine, the FDA discourages scheduling separate sessions purely for photos or videos. Ultrasound energy can slightly heat tissues and, in some cases, create tiny gas pockets in fluid. These effects are minimal during a standard medical scan, but the long-term consequences of prolonged or unnecessary exposure aren’t fully understood.
The FDA also warns against over-the-counter fetal heartbeat monitors sold directly to parents. These devices, when used by untrained people, can expose the baby to extended ultrasound energy and produce readings that are easy to misinterpret.
What Determines Your Personal Schedule
Your actual number of ultrasounds will depend on your specific situation. A straightforward pregnancy with no complications might involve just two scans total. A pregnancy with gestational diabetes, high blood pressure, or a baby whose growth curve looks unusual could involve six, eight, or more. Certain infections during pregnancy trigger their own monitoring protocols: parvovirus, for example, calls for scans every one to two weeks for about 12 weeks after infection.
If you’re unsure why a scan is being ordered or feel like you’re getting more (or fewer) than you expected, ask your provider what they’re looking for. Each ultrasound should have a clear clinical purpose, whether that’s dating the pregnancy, checking anatomy, tracking growth, or assessing the baby’s well-being in the final stretch.