Most pregnant people get two ultrasounds during a routine, low-risk pregnancy. The first is typically a dating scan in the first trimester, and the second is the anatomy scan between 18 and 22 weeks. That said, many people end up having more than two, depending on their age, health conditions, and how the pregnancy progresses.
The American College of Obstetricians and Gynecologists (ACOG) recommends at least one standard ultrasound exam, performed at 18 to 22 weeks. A first-trimester scan isn’t technically required for every pregnancy, but most OB practices in the U.S. now include one as part of routine care. Beyond those two, additional scans are ordered based on specific medical reasons rather than a fixed schedule.
The First Trimester Scan (6 to 13 Weeks)
If you have a first-trimester ultrasound, it usually happens between 6 and 13 weeks. The primary goals are confirming the pregnancy is in the uterus, checking for a heartbeat (which becomes visible around 6 weeks), and determining how far along you are. The technician measures the length from the top of the baby’s head to its bottom, called the crown-rump length. This measurement is the most accurate way to estimate your due date up through about 11 weeks.
This scan also checks for twins or other multiples by counting the number of gestational sacs and heartbeats. In early pregnancy, especially before 11 weeks, the scan is usually done transvaginally with an internal probe, which produces a much clearer image at that stage than the traditional belly scan. From around 11 or 12 weeks onward, abdominal ultrasound becomes the standard approach.
The Anatomy Scan (18 to 22 Weeks)
The mid-pregnancy anatomy scan is the most detailed ultrasound you’ll have. This is where the technician systematically checks the baby’s organs, brain, spine, heart, and limbs. They also measure the head diameter, head circumference, abdominal circumference, and thigh bone length to confirm the baby is growing on track for its age. Beyond the baby itself, the technician evaluates the amount of amniotic fluid, blood flow through the umbilical cord, and the position of the placenta.
This is the scan where many parents learn the baby’s sex, though that’s optional. It typically takes 30 to 45 minutes because the technician is working through a long checklist. Sometimes the baby’s position makes it hard to see everything, and you may be asked to come back for a follow-up to complete the survey.
Why You Might Get More Scans
Two scans is the baseline, but plenty of pregnancies involve more. Your provider will order additional ultrasounds if there’s a clinical reason, and those reasons range from minor to serious. Common situations that add scans to your schedule include:
- Bleeding or cramping in early pregnancy: An early scan to confirm viability and rule out ectopic pregnancy.
- Size discrepancies: If your belly measures larger or smaller than expected at a prenatal visit, a growth scan checks whether the baby’s size matches its gestational age.
- Gestational diabetes or high blood pressure: These conditions increase the risk of growth problems, so periodic growth checks become part of monitoring.
- Placenta concerns: If the anatomy scan shows the placenta is covering or near the cervix, a follow-up scan later in pregnancy confirms whether it has moved.
- Low or high amniotic fluid: Either extreme requires closer surveillance.
For pregnancies over 40, providers often add third-trimester growth scans, though ACOG notes there isn’t firm evidence guiding exactly when or how often to do them. For those aged 35 to 39 without other risk factors, extra scans aren’t automatically recommended.
Twin Pregnancies Have a Different Schedule
If you’re carrying twins, your ultrasound calendar looks very different from a singleton pregnancy. The number of scans depends on whether the babies share a placenta.
Twins with separate placentas (dichorionic) are typically scanned at 12 weeks, 20 weeks, and then every four weeks until delivery. That works out to roughly six to eight scans total. Twins sharing a placenta (monochorionic) need closer monitoring because of the risk of uneven blood flow between the babies. These pregnancies are scanned at 12 and 16 weeks, then every two weeks until delivery, which can mean 12 or more ultrasounds over the course of the pregnancy.
Late-Pregnancy Monitoring Scans
Some pregnancies require specialized monitoring in the third trimester that goes beyond a standard growth scan. One common tool is the biophysical profile, which uses ultrasound to evaluate five areas: the baby’s heart rate, breathing movements, body movements, muscle tone, and the amount of amniotic fluid. Each area is scored 0 or 2 points, for a total of up to 10. A score of 8 to 10 is reassuring. A score of 6 is considered borderline and usually means a repeat test within 12 to 24 hours. A score of 4 or below typically leads to a conversation about early delivery.
You’re most likely to have a biophysical profile if your pregnancy goes past your due date, if you have a chronic health condition, or if there are concerns about fetal growth or amniotic fluid levels. Some higher-risk pregnancies involve weekly or twice-weekly biophysical profiles in the final weeks.
Are Extra Ultrasounds Safe?
Ultrasound uses sound waves, not radiation, and has a strong safety record spanning more than 20 years of use. It does not carry the risks associated with X-rays or CT scans. That said, the FDA notes that ultrasound energy can slightly heat tissues and, in some cases, create tiny gas pockets in body fluids. The long-term effects of these phenomena aren’t fully understood, which is why the general principle is to use ultrasound when there’s a medical reason rather than for extended or unnecessary sessions.
The FDA specifically discourages non-medical “keepsake” ultrasound sessions at boutique studios, where untrained operators may expose the baby to prolonged energy. Getting a photo or short video clip during a medically indicated scan is perfectly fine. The concern is with extra sessions that serve no diagnostic purpose and may last longer than a clinical exam would. The same caution applies to over-the-counter fetal heartbeat monitors, which the FDA says should only be used by trained providers.
What a Typical Count Looks Like
For a straightforward, low-risk pregnancy, two to three ultrasounds is normal. Most people get a first-trimester dating scan and the 18-to-22-week anatomy scan. Some also get one late-pregnancy scan to check growth or placenta position. If your pregnancy involves complications, chronic conditions, or multiples, you could easily have six to twelve or more. The number itself doesn’t signal a problem. It simply reflects how closely your particular pregnancy needs to be watched.