Scans During Pregnancy: Types, Timeline & Why They Are Important

Somewhere around week 6, most women get handed a slip of paper with a scan date on it, and that's usually the first real "this is happening" moment of pregnancy. After that, the scans keep coming, roughly one every few weeks, right up until delivery.

A lot of expecting mothers assume every scan is basically the same thing repeated. It isn't. The 8-week scan is checking something completely different from the one at 20 weeks, which is again different from what happens at 32 weeks. Each one has a job to do, and skipping one because "we already did a scan last month" isn't really how it works.

Below is a rundown of every scan you'll likely come across during a normal pregnancy, roughly when it happens, and what your doctor is actually looking for each time.

Types of Scans During Pregnancy

1. Dating (Viability) Scan (6-10 Weeks)

This is the first scan most women will have, and its job is fairly simple: confirm that the pregnancy has actually implanted in the uterus. That might sound like an odd thing to check, but occasionally a pregnancy implants outside the uterus, usually in a fallopian tube. That's called an ectopic pregnancy, and it needs to be ruled out early.

Around 6 weeks, a heartbeat is often visible on the screen, which is one of the more emotional moments for a lot of parents. The scan also measures the gestational sac and the embryo, which is how your due date gets calculated, and it'll tell you fairly quickly if there's more than one baby in there.

2. NT Scan (Nuchal Translucency) (11-14 Weeks)

The NT scan looks at a small pocket of fluid at the back of the baby's neck. If that fluid measurement is on the thicker side, it can be an early signal for chromosomal conditions like Down syndrome. Doctors usually pair this scan with a blood test, since the two together give a more reliable risk estimate than either one alone.

One thing worth remembering here: this is a screening test, not a diagnosis. A higher-risk result doesn't mean a positive diagnosis. It just means your doctor will probably want to follow up with more specific testing before drawing any conclusions.

3. Anomaly Scan/TIFFA (18-22 Weeks)

TIFFA, or Targeted Imaging for Fetal Anomalies, is one of the most important scans during pregnancy. It is also called the anomaly scan, level II scan, anatomy scan, or simply the 20-week scan. It is basically a thorough head-to-toe check of the baby: the brain, spine, heart, kidneys, limbs, and a few other structures, with the doctor looking for anything that doesn't look quite right structurally. Along the way, they'll also check where the placenta has settled and how much amniotic fluid is surrounding the baby. 

4. Fetal Echocardiography (18-24 Weeks)

The anomaly scan is a much closer look at the structure and function of the baby's heart. Doctors tend to recommend it if there's a family history of heart defects, if the mother has diabetes, or if something on an earlier scan raised a question worth a second look.

5. Growth Scan (28-32 Weeks and Beyond if Needed)

By the third trimester, the conversation shifts from "is everything developing correctly" to "how well is the baby growing." This scan measures the head, abdomen, and thigh bone, then compares those numbers against expected growth curves for that stage.

If your baby seems to be tracking small or unusually large for their age, your doctor may want to repeat this scan a few times over the following weeks rather than waiting for the next scheduled visit.

6. Doppler Scan (24-40 Weeks)

Doppler scans use sound waves to measure blood flow, specifically through the umbilical cord and placenta, and sometimes through the baby's own blood vessels. It's really a way of checking whether the baby is getting enough oxygen and nutrition.

This USG is recommended more often in pregnancies involving high blood pressure, slower-than-expected fetal growth, or a noticeable drop in fetal movement, though some doctors include it in routine third-trimester monitoring regardless.

7. 3D/4D Scan (26-32 Weeks)

Unlike other scans, this pregnancy scan isn't medically necessary for most low-risk pregnancies. A 3D scan gives a more lifelike still image of the baby's face and body, while 4D adds motion, essentially a short video.

Most parents get this done purely for the experience of seeing the baby clearly before birth. Occasionally, though, it does help a doctor get a better view of a facial or limb feature that needs a closer look after an earlier scan.

List of Scans During Pregnancy (Complete Table)

Here’s a list of scans performed  during pregnancy:

This isn't a fixed table for everyone. It shifts depending on your health history, how the pregnancy is going, and what your doctor's usual practice is. Higher-risk pregnancies almost always mean more frequent scans than what's listed here.

Are Pregnancy Scans Safe?

Yes. Ultrasound doesn't use radiation, unlike an X-ray or CT scan. It uses sound waves instead, which is exactly why it's the go-to imaging method throughout pregnancy.

That said, "safe" doesn't mean "do it as often as you like." Scans should happen when there's a medical reason for them or when your doctor recommends one, not just for extra reassurance every few weeks.

Does a High-Risk Pregnancy Need Extra Scans?

Generally, yes. A few conditions that usually mean more frequent monitoring:

• Gestational diabetes or pre-existing diabetes
• High blood pressure or preeclampsia
• A prior miscarriage or preterm delivery
• Carrying twins or more
• Slower-than-expected fetal growth
• Placental complications, such as placenta previa

How to Prepare for Ultrasound in Pregnancy

Preparation varies a bit depending on which scan you're having, but a few things apply across most appointments:

• Early scans often require a full bladder, since that makes the uterus easier to image clearly.
• Wear something loose and comfortable that gives easy access to your abdomen.
• Bring along your previous scan reports and any prescriptions, so your doctor can compare against earlier results.
• If lying flat right after a heavy meal makes you uncomfortable, eat lighter beforehand.
• When in doubt, just ask your clinic ahead of time if that particular scan needs anything specific from you.

Also Read: Importance of Ultrasound in Pregnancy

What Happens If a Scan Shows a Concern?

A flagged result doesn't automatically mean something is wrong. It may just need a second look before anyone draws conclusions.

Depending on what came up, your doctor might suggest:

• A repeat scan - to see if the finding has changed or resolved after a few weeks
• A specialist referral - to a fetal medicine expert or a paediatric cardiologist, depending on the concern
• Further testing - blood work, amniocentesis, or more detailed imaging to get a clearer answer
• Closer monitoring - simply more frequent visits and scans going forward

What matters most is having an honest conversation with your doctor about exactly what was seen, rather than jumping to conclusions from a single report. At Apollo Cradle, one of the best hospitals for pregnancy in Hyderabad, Bangalore, Chennai, and other cities, the fetal medicine team walks parents through the findings step by step and explains what the next steps will involve.