How Many Ultrasound Scans During Pregnancy? | Scan Schedule

Ultrasounds can feel like the fun part of prenatal care. You see movement, hear timing details, and leave with a clearer picture of how the pregnancy is going. Then the calendar gets confusing. One clinic offers two scans. Another lists four. A friend had weekly checks late in pregnancy. So what’s normal?

The clean answer is this: there isn’t one universal number. Scan schedules change based on where you get care, how your pregnancy is dated, what your screening choices are, and whether anything pops up that needs a closer look. Still, you can predict a “typical” range and know what triggers extra scans so you’re not caught off guard.

This article walks through the routine scan pattern for a low-risk pregnancy, the scan types you may hear about, and the common reasons scan counts rise. You’ll also get a practical way to ask for clarity without feeling pushy.

How Many Ultrasound Scans During Pregnancy? For Low-Risk Care

For many people with a low-risk pregnancy, two scans are the standard baseline:

• An early scan in the first trimester to confirm dating, check for multiples, and see early pregnancy structures.
• A mid-pregnancy anatomy scan at about 18–22 weeks to check fetal anatomy and placenta position.

This matches how many public systems describe routine care. In the UK, many hospitals offer at least two scans, one at 11–14 weeks and one at 18–21 weeks, often called the “12-week scan” and the “20-week scan.” That’s laid out on the NHS ultrasound scans in pregnancy page.

In the US, care can look more varied, yet the core idea stays similar: at least one standard ultrasound is commonly done at 18–22 weeks, with earlier scanning used for dating or specific clinical reasons. The ACOG ultrasound exams FAQ describes that baseline and explains why some people get more than one scan.

If you’re trying to sanity-check a plan, here’s a plain rule of thumb: if everything is straightforward and dating is clear, you’ll often see two routine scans. If dating is uncertain, symptoms arise, or a condition needs tracking, the count rises.

Ultrasound Scan Timeline By Trimester

First Trimester Scans

Early scans tend to answer a few practical questions: How far along are you? Is the pregnancy in the uterus? Is there more than one fetus? Is there a heartbeat when timing makes that visible?

Some clinics schedule a dating scan as routine. Others rely on the last menstrual period when it’s reliable and reserve an early scan for specific reasons like bleeding, pain, uncertain dates, or prior pregnancy history. You may also hear about a nuchal translucency measurement done with early screening in some settings.

If you have irregular cycles, recently stopped hormonal birth control, or aren’t sure of the first day of your last period, an early scan can prevent weeks of confusion later. It can also cut down on “you might be overdue” stress near the end of pregnancy.

Second Trimester Scans

The mid-pregnancy anatomy scan is the one most people think of when they say “the big ultrasound.” It’s usually done in the 18–22 week window. The sonographer checks fetal anatomy and growth measurements, amniotic fluid appearance, placenta location, and often the cervix, depending on the clinic and the image quality that day.

This scan can take longer than you expect. The goal is a full set of views. If the fetus is facing the wrong way or moving nonstop, you might be asked to change position, take a short walk, or come back for a repeat visit. A repeat visit doesn’t automatically mean something is wrong. Sometimes it’s just a camera-angle problem.

Third Trimester Scans

In a low-risk pregnancy, a third-trimester ultrasound may not be routine. Many people won’t get one unless there’s a reason to check growth, amniotic fluid, placenta position, fetal presentation, or another clinical question.

On the flip side, some practices do schedule a late growth scan for certain groups, like people with prior growth issues, medical conditions, or a higher chance of placenta problems. If your clinician says you’ll have a third-trimester scan, ask what question it’s meant to answer. A scan with a purpose is easier to understand and easier to interpret.

There’s also a global angle here: the World Health Organization recommends at least one ultrasound before 24 weeks for dating and to help detect issues like multiple pregnancy and fetal anomalies. The WHO lays this out in its brief on imaging ultrasound before 24 weeks of pregnancy.

What Each Scan Type Is Trying To Confirm

Scan names can sound like a different language. A useful way to decode them is to ask, “What question is this scan answering?” When you know the question, the timing makes more sense, and the result feels less mysterious.

Some ultrasounds are broad and check a full set of structures. Others are “targeted” and zoom in on one issue, like placenta location or cervical length. Some are brief and confirm a single point, like fetal presentation near term.

Clinics also differ in how they label scans. One practice may call a scan “growth.” Another may call it “third-trimester assessment.” A hospital ultrasound unit may use “limited” or “follow-up” in the report. The label matters less than the goal.

Professional guidance on what a standard obstetric ultrasound should include is described in joint practice parameters. If you’re curious about what’s generally checked in standard exams across pregnancy, the ACR–ACOG–AIUM–SMFM–SRU practice parameter outlines the elements of standard first-, second-, and third-trimester exams.

Common Ultrasound Types And Typical Timing

This table shows the scan types people hear about most often, when they’re usually done, and what they’re meant to check. Timing can shift by region and clinic.

Scan Type	Typical Timing	Main Purpose
Dating or viability scan	Early first trimester	Confirm gestational age, location, heartbeat when visible
Nuchal translucency measurement	11–14 weeks	Part of some screening pathways, adds detail to risk estimates
Early anatomy or targeted first-trimester scan	12–14 weeks	Closer look when history or findings call for it
Standard anatomy scan	18–22 weeks	Assess fetal anatomy, placenta position, growth measures
Placenta follow-up scan	Later second trimester or third trimester	Recheck placenta location if it was low earlier
Growth scan	Third trimester	Estimate growth trends and amniotic fluid appearance
Biophysical profile (BPP)	Third trimester when indicated	Combine ultrasound markers with fetal well-being checks
Presentation check	Late pregnancy	Confirm head-down vs breech and position details

Why Some Pregnancies Need More Scans

Extra ultrasounds usually fall into one of three buckets: dating clarity, symptom checks, or tracking a known condition. Some of the most common reasons include bleeding or pain early on, uncertain dates, twins or higher-order multiples, or a medical condition that changes pregnancy monitoring.

Sometimes a “more scans” plan is also about image quality. If a key view can’t be captured at the anatomy scan, a repeat visit can be scheduled to finish the checklist. That’s more about geometry than about bad news.

Late in pregnancy, scan frequency can rise if growth tracking is needed or if fetal presentation and placenta position need confirmation for delivery planning. In those cases, ultrasounds are used like snapshots in a time series. One image is helpful. A pattern is often more helpful.

Dating Issues That Add Scans

If the first weeks are hazy, scan counts rise fast. Irregular periods, uncertain last menstrual period dates, or a large gap between “expected” and “measured” gestational age can trigger an early scan plus a follow-up to confirm growth progression. Clinicians like clear dating because it affects decisions later, such as when to treat a pregnancy as post-term.

Conditions That Often Add Growth Or Fluid Checks

Some conditions are linked with growth changes or placenta issues, so clinicians track growth and fluid later in pregnancy. You might see this with high blood pressure disorders, diabetes in pregnancy, certain autoimmune conditions, or a history of growth restriction. If you’re in a higher-monitoring group, ask what measurements will be tracked across visits. It helps you interpret each report.

Multiples And Scan Frequency

Twins and higher-order multiples usually mean more ultrasounds. There are more things to track: growth patterns for each fetus, fluid for each sac, placenta structure, and signs of complications that are specific to multiples. The schedule can range from “a few extra” to fairly frequent scans, depending on chorionicity and other factors.

What Ultrasound Can And Can’t Tell You

Ultrasound is strong at visual structure: organs, limbs, placenta, amniotic fluid, and growth measurements. It can also show blood flow patterns with Doppler when that’s indicated, and it can help assess fetal presentation late in pregnancy.

Still, it has limits. Some findings are subtle. Some conditions don’t show up on imaging. Some views can’t be captured if the fetal position blocks them. Also, ultrasound dating becomes less precise later in pregnancy, so early dating has outsized value.

When a report mentions “limited views,” it often means the sonographer couldn’t get all the angles needed that day. That’s often solved with a repeat scan. When a report mentions a “finding,” ask what category it falls into:

• A normal variation with no follow-up needed
• A finding that needs a recheck for clarity
• A finding that changes monitoring or triggers another test

This framing keeps your brain from jumping to worst-case conclusions. It also helps you ask sharper questions in the follow-up visit.

How To Talk With Your Clinician About Scan Count

If you feel unsure about how many scans you’ll get, ask for the plan in plain language. You don’t need to speak in medical terms. A few direct questions can clear it up fast:

• “Which scans are routine in this clinic for low-risk care?”
• “What question is this scan answering?”
• “If today’s images are incomplete, what’s the usual next step?”
• “If I need extra scans later, what would trigger that?”

If you’re comparing practices or moving care mid-pregnancy, ask for your prior ultrasound reports and image summaries. That way the new clinic isn’t guessing. It can also reduce repeat scans that are only needed because records are missing.

Reasons Ultrasound Counts Rise And What To Ask

This table lists common “extra scan” triggers and a quick question that can help you understand the plan without spiraling.

Reason More Scans Are Scheduled	What The Clinic Is Tracking	One Good Question To Ask
Uncertain dates	Growth over time to confirm gestational age	“Will this change my due date?”
Bleeding or pain	Pregnancy location, heartbeat timing, placenta checks	“What signs should make me call right away?”
Incomplete anatomy views	Missing angles from the anatomy scan	“Which views were missing?”
Low-lying placenta earlier	Placenta position later in pregnancy	“When do you recheck placenta location?”
Growth concerns	Estimated growth trend and fluid checks	“Are we tracking a trend or one measurement?”
Multiples	Growth for each fetus and placenta-related risks	“What type of twins does this appear to be?”
Medical condition in pregnancy	Growth, fluid, blood flow patterns when indicated	“What are we checking each time?”

Safety Basics And Why Scan Purpose Matters

Ultrasound uses sound waves, not ionizing radiation. In routine prenatal care, it’s widely used and generally considered safe when performed for medical reasons and with appropriate settings. That’s also why clinicians try to avoid “just for fun” scanning. A scan should have a clear goal. A clear goal keeps exposure as low as is practical and keeps the result easier to interpret.

If you’re offered a scan and you’re unsure why, ask what it’s meant to confirm. If the clinic can’t name a reason, it’s fair to ask whether the scan can be skipped. If there is a reason, you’ll usually feel better once you know what that reason is.

Practical Takeaways You Can Use At Your Next Appointment

If you want a simple way to leave your next visit with clarity, try this three-part check:

• Count the routine scans. Ask which ones are standard in that clinic for low-risk care.
• Name the goal. For every additional scan, ask what question it answers.
• Map the timeline. Ask when results will be rechecked, if a follow-up is expected.

For many low-risk pregnancies, the count stays close to two. If your plan includes more, it usually reflects dating clarity, symptom follow-up, or tracking a known risk. Once you know which bucket you’re in, the schedule feels less random and more like a plan.