The 20-week morphology scan

The morphology scan — also called the 20-week scan or anatomy scan — is the most detailed look at your baby you’ll get before birth, and for many parents it’s also the most exciting. It’s usually done between about 18 and 22 weeks, and while there’s a lot going on behind the scenes medically, it’s often the moment you get to watch your baby wriggle, yawn and stretch on the screen.

What it’s for. The main purpose is a thorough health check. Over roughly 30 to 45 minutes, the sonographer carefully works through your baby’s anatomy and development, measuring and examining:

• The brain and skull, face (including the lips), and spine
• The heart — its structure and the way blood flows through it
• The chest and lungs, the stomach, kidneys and bladder, and the abdominal wall
• The arms, legs, hands and feet, and the bones
• Your baby’s growth (measurements are compared to what’s expected for the dates)
• The placenta’s position, the umbilical cord, and the amount of amniotic fluid around your baby

Checking the placenta matters because if it’s lying low (near or over the cervix), you’ll usually be offered a follow-up scan later to see whether it has moved up, as most do.

Can you find out the sex? Usually yes, if you’d like to and your baby is in a cooperative position — the morphology scan is when many people find out. If you’d rather keep it a surprise, tell the sonographer at the start (it can help to note it on your referral), so they don’t mention it. Some clinics can write it in a sealed envelope for a reveal later.

What it’s like. It’s the same as other pregnancy ultrasounds: gel on your tummy and a handheld probe moved across your skin. You may be asked to come with a comfortably full bladder. There’ll be quiet stretches while the sonographer concentrates on measurements — this is normal and doesn’t mean something’s wrong; they’re simply working methodically and can’t always chat and measure at once. Usually they’ll then turn the screen to you and point out what they can see. Bring your partner or a support person if you can; it’s a lovely one to share.

If something needs a closer look. Most morphology scans are reassuring. Sometimes the sonographer can’t get a clear view of everything (babies are wriggly, and their position matters), and you may simply be asked to come back or go for a walk and return so they can finish. Occasionally the scan picks up something that needs further assessment — this might be a “soft marker” (a minor finding that’s often a normal variation) or something that warrants more tests or a specialist opinion. If that happens, try not to jump to the worst conclusion: your care team will explain clearly what they’ve seen, what it might mean, and what the next steps are, and many findings turn out to be nothing of concern.

A few practical notes. The scan is Medicare-rebatable, though there may be an out-of-pocket cost depending on where you go, so it’s worth asking when you book. It’s usually a separate appointment at an imaging clinic, and results go to your GP, midwife or obstetrician, who’ll talk through them with you at your next visit. Photos or digital images are often available, though what’s included varies from clinic to clinic.

A little preparation helps the day go smoothly. Wear a two-piece outfit so you only need to lift your top rather than undress, follow any instructions about your bladder (some clinics ask you to arrive with it comfortably full), and allow plenty of time — the scan is long, and your baby’s position may mean the sonographer needs you to wait, walk around, or come back to get a clear view of everything. If your baby is being uncooperative, that’s completely normal and not a concern.

You may also be offered 3D or 4D “keepsake” images at some private clinics for an extra fee — these are purely for the lovely pictures, separate from the medical scan, and entirely optional. And if your placenta is low, or your baby is measuring smaller or larger than expected, you’ll simply be booked for a follow-up growth scan later in pregnancy to keep an eye on things — a routine next step, not a cause for alarm.

It’s completely normal to feel a mix of excitement and nerves beforehand, especially if you’ve been anxious about the pregnancy — the wait for reassurance can be the hardest part. Whatever you’re feeling is okay. And remember that while its real job is a careful health check, the morphology scan is also a rare, wonderful chance to meet your baby for a while before the big day. If you have any questions before or after, your midwife or doctor is the best person to talk them through with.