Pregnancy Scan Schedule: What Each Ultrasound Checks, Trimester by Trimester

By the Lalwani Mother and Child Care team, Pune  |  Author & medically reviewed by: Dr. Mahima Lalwani |  Last reviewed: October 2026

Quick answers •    Typical schedule: an early scan around 6 to 9 weeks if needed, the NT scan at 11 weeks to 13 weeks 6 days, the anomaly scan at 18 to 22 weeks, and a growth scan around 28 to 32 weeks. •    How many scans? For an uncomplicated pregnancy, many Indian clinics do about four to five. Your doctor decides, and high-risk pregnancies need more. •    Is ultrasound safe? Current diagnostic ultrasound has no independently confirmed harmful effects in humans, and it should be used only when it gives a medical benefit. •    Will the scan tell us the baby’s sex? No. In India, determining the sex of the baby is prohibited under the PCPNDT Act.

 

Pregnancy scans can feel like a list of dates and terms. What is a dating scan? Why is the NT scan so early? What can the 20 week scan see, and what can it miss? This guide explains the pregnancy scan schedule in plain language: when each ultrasound during pregnancy is usually done, what it checks, how to prepare, and when your doctor may advise extra scans. Timings vary between clinics and between pregnancies, so your own doctor’s plan comes first.

Trimester wise scans: the pregnancy scan schedule at a glance

A usual schedule for an uncomplicated pregnancy looks like this. Weeks are counted from the first day of your last period.

Trimester	Scan	Usual timing	Main purpose
First	Early (dating or viability) scan	6 to 9 weeks, if advised	Confirms the pregnancy is in the uterus, checks the heartbeat, counts the babies and estimates dates
First	NT scan (nuchal translucency)	11 weeks to 13 weeks 6 days	Screens for chromosomal conditions and gives an early look at the baby; also confirms dates
Second	Anomaly scan (Level 2, TIFFA), often called the 20 week scan	18 to 22 weeks	Detailed check of the baby’s organs and body structure, plus placenta and fluid
Third	Growth scan	About 28 to 32 weeks	Checks growth, estimated weight, fluid, placenta position and baby’s position
Third	Doppler scan	After 28 weeks, only when advised	Checks blood flow between the placenta and baby in higher-risk pregnancies

 

The timings above follow the ISUOG first-trimester guideline and Indian hospital scan guides. They are typical, not fixed. Your doctor may move or add scans based on your health, your dates and your baby’s growth.

How many ultrasounds in pregnancy do you need?

There is no single number for everyone. Indian hospital guides, such as Hinduja Hospital’s, describe the minimum routine scans for a normal pregnancy as a dating scan, an NT scan, an anomaly scan and one or two growth scans, which is about four to five scans. Additional scans are advised only when there is a medical reason.

You may need more scans if you are expecting twins, have diabetes or high blood pressure, had a baby with growth problems before, have bleeding, or your baby is measuring small or large. A scan should always have a medical reason, and you are welcome to ask your doctor why a scan is advised. Our high risk pregnancy care page lists the conditions we monitor more closely.

What is a dating scan, and when is it done?

A dating scan is an early ultrasound that confirms how many weeks pregnant you are and sets your due date. In India it is commonly done at about 6 to 9 weeks, when it also confirms that the pregnancy is inside the uterus, checks for a heartbeat and shows whether you are expecting more than one baby.

Dating by the size of the baby, measured from head to bottom (crown-rump length), is the most accurate way to estimate dates in early pregnancy. The ISUOG guideline says it is accurate to within about 5 days in 95% of cases. Not every woman needs a scan at 6 to 9 weeks. If your dates are certain and you have no bleeding or pain, your doctor may use the NT scan for dating.

Early scans can be done on the abdomen or, in very early pregnancy, internally with a thin probe (transvaginal). Both are standard, and your sonographer will explain which is needed.

NT scan in pregnancy: what is it, and when to do it?

The NT scan is done between 11 weeks and 13 weeks 6 days of pregnancy. It measures a small fluid-filled space at the back of the baby’s neck, called the nuchal translucency, and is used with a blood test to screen for chromosomal conditions such as Down syndrome.

This is the answer to “when to do an NT scan in pregnancy”: within that window, which corresponds to a baby measuring 45 to 84 mm from head to bottom. If you miss the window, ask your doctor what options remain.

• It is a screening test, not a diagnosis. A “higher chance” result does not mean the baby has a condition. It means your doctor will explain further options, such as additional tests.
• It is combined with a blood test. The ISUOG guideline notes that NT is combined with blood markers (free beta-hCG and PAPP-A) to improve screening performance.
• The operator matters. The guideline advises that only trained and certified operators should do the NT measurement, so it is reasonable to ask who will do your scan and how they are trained.
• The scan also checks: the baby’s heartbeat, size, number of babies, the placenta and early body structures, and confirms your due date.

What does a 20 week scan check? The anomaly scan explained

The anomaly scan, often called the 20 week scan or the level 2 scan, is a detailed check of the baby’s body. It is usually done between 18 and 22 weeks, and it looks at the baby’s brain, spine, heart, face, abdomen, limbs and other structures, along with the position of the placenta and the amount of amniotic fluid.

Indian hospital guides give a window of 18 to 22 weeks, while NHS trusts in England use about 18 weeks 6 days to 20 weeks 6 days. Your doctor will pick the week that suits your dates, so book the scan early enough to fit the window.

What the anomaly scan can and cannot tell you

• It screens for physical differences in how the baby has developed. It is not a guarantee that everything is normal.
• It cannot find every condition. One NHS trust notes that it picks up only about 60% of heart problems, and some babies are born with differences that were not seen on the scan.
• The baby’s position, your body weight or abdominal scarring can make some views hard. If the views are incomplete, you may be called back for a repeat scan. This does not by itself mean something is wrong.
• If a concern is found, your doctor will explain it and may arrange another scan or a referral to a specialist team.

Growth scan in the third trimester: when and why?

A growth scan in the third trimester measures the baby’s size and estimated weight, the amount of amniotic fluid, the position of the placenta and the baby’s position. In many Indian clinics it is done at about 28 to 32 weeks, and a second one may follow.

Practice differs. Some guidelines, such as New Zealand’s obstetric ultrasound guideline (2019), treat third-trimester scans as based on a reason, not as routine, for example diabetes, suspected slow growth, a low-lying placenta, reduced movements, twins or a baby in an unusual position. So whether you need one, and how many, is a decision for you and your doctor.

Growth is judged against charts and over time, not from a single number, so repeat growth scans are spaced at least 14 days apart. If you have gestational diabetes, your doctor may plan growth scans at regular intervals.

Doppler and 3D or 4D scans

A Doppler scan checks blood flow between the placenta and the baby. It is usually advised after 28 weeks in higher-risk pregnancies, for example with high blood pressure, diabetes or slow growth, and is not needed in most uncomplicated pregnancies.

3D and 4D scans give a more lifelike picture of the baby’s face and movements, usually after 26 weeks. They are optional and do not replace the medical scans. Ultrasound should be used by qualified professionals for medical benefit, so ask your doctor before booking a scan for a reason other than your care.

Is ultrasound safe during pregnancy?

Yes, when done for a medical reason by a trained professional. The American Institute of Ultrasound in Medicine (AIUM) states there are “no independently confirmed adverse effects” in humans from current diagnostic ultrasound equipment. Ultrasound uses sound waves, not radiation.

Professional bodies follow the ALARA principle: keep the exposure “as low as reasonably achievable”. Sonographers do this by using the right settings and not scanning longer than needed. Because the benefit of a scan comes from the information it gives, scans are advised when there is a clear reason, not just for reassurance.

Can the scan tell us the baby’s sex?

No. In India, the Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act, 1994 prohibits determining the sex of a fetus, including by ultrasound. Centres that perform pregnancy scans are bound by it, and the sex of the baby will not be shared with you. This is different from some other countries, where sonographers may mention it if asked.

How to prepare for your pregnancy scans

• Follow the centre’s instructions on water. Some scans need a comfortably full bladder. For example, one NHS trust asks women to drink 1 to 2 pints of water (about 600 ml to 1 litre) about an hour before the anomaly scan.
• Carry your previous reports and your antenatal records, including blood tests.
• Wear loose, two-piece clothing so the abdomen is easy to reach.
• Plan your time. Scans usually take about 20 to 30 minutes, and the anomaly scan can take longer if the baby is in a difficult position.
• Bring one companion if the centre allows it, and write your questions down beforehand.
• Ask for the findings in simple words. The sonographer or your doctor should explain what was seen and what happens next.

Pregnancy ultrasound in Pune: sonography at Lalwani Mother and Child Care

If you are looking for a sonography center in Pune, or a pregnancy ultrasound in Pune, our sonography service offers antenatal and obstetric sonography, including anomaly scans, in 2D and 3D. Our maternity and obstetrics service lists dating, NT, anomaly, growth and Doppler scans among its pregnancy scans and diagnostic tests, so you can plan your NT scan on Pune Satara Road and your anomaly scan in Pune alongside your regular antenatal checkups.

Your obstetrician reviews each scan with you and advises what comes next. You can read about our consultants on the doctors page. If your pregnancy needs closer monitoring, high risk pregnancy care and a NICU and PICU are at the same maternity hospital in Pune, with 24-hour emergency services.

Address	Pune Satara Road, Opposite NEXA Showroom, Near Chandukaka Saraf, Pune 411 009
Phone	020 68686868
Hours	Monday to Sunday, 8:00 am to 9:00 pm. 24-hour emergency services available

 

When to call your doctor, even between scans

Do not wait for your next scan if you have:

• Vaginal bleeding or leaking of fluid
• Severe or persistent abdominal pain
• Your baby moving much less than usual
• A severe headache, blurred vision or sudden swelling of the face and hands
• Fever, or burning when you pass urine

Frequently asked questions

1. What is the pregnancy scan schedule
   A usual schedule is an early scan at 6 to 9 weeks if needed, an NT scan at 11 weeks to 13 weeks 6 days, an anomaly scan at 18 to 22 weeks, and a growth scan at about 28 to 32 weeks. Doppler and extra scans are added only when your doctor advises them.
2. How many ultrasounds are done in pregnancy?
   For a normal pregnancy, many Indian clinics do about four to five: dating, NT, anomaly and one or two growth scans. The number depends on your health and your baby’s growth, and high-risk pregnancies need more.
3. When to do the NT scan in pregnancy?
   The NT scan is done between 11 weeks and 13 weeks 6 days, when the baby measures about 45 to 84 mm from head to bottom. It is a screening test and is usually combined with a blood test.
4. What does a 20 week scan check?
   The 20 week anomaly scan checks the baby’s brain, spine, heart, face, abdomen and limbs, along with the placenta position and amniotic fluid. It is usually done between 18 and 22 weeks and cannot detect every condition.
5. What is a dating scan?
   A dating scan is an early ultrasound that confirms how many weeks pregnant you are and your due date. It also checks the heartbeat and number of babies, and that the pregnancy is in the uterus. In India it is commonly done at 6 to 9 weeks.
6. Is a growth scan necessary in the third trimester?
   Not for everyone. Many Indian clinics do one or two growth scans at about 28 to 32 weeks, while some guidelines advise them only when there is a reason, such as diabetes or slow growth. Your doctor will advise what suits you.
7. Is ultrasound safe during pregnancy?
   Yes, when used for a medical reason by a trained professional. The AIUM reports no independently confirmed adverse effects in humans from current diagnostic ultrasound. Ultrasound uses sound waves, not radiation, and professionals follow the ALARA principle.
8. Will the ultrasound tell us if it is a boy or girl?
   No. The PCPNDT Act, 1994 prohibits determining the sex of the baby in India, including by ultrasound, so your scan report will not mention it.
9. Do I need a full bladder for a pregnancy scan?
   Sometimes. Early scans and some later scans work better with a comfortably full bladder, but the instructions differ between centres. Ask the centre when you book, and do not hold urine if it becomes uncomfortable.