18 Weeks Pregnant: Morphology Scan, First Flutters & Symptoms
At 18 weeks pregnant, your baby is about the size of a capsicum and is rolling, flipping and stretching. You might feel their first flutters soon, if you haven't already. This is also when many people have their morphology scan, a detailed look at how your baby is growing.
- Baby's size
- About the size of a capsicum (around 14cm, 190g)
- Big development
- Lungs developing and nerves maturing
- Common symptoms
- A bigger appetite, swelling, back pain and trouble sleeping
- This week
- Your morphology scan, between 18 and 20 weeks
What's happening this week
There's still lots of room in your uterus, so your baby is moving freely. Their organs are formed, and they're busy maturing.
Moving
Busy acrobatYour baby rolls, twists and flips, and they yawn, suck and swallow. You may soon feel these movements as flutters or bubbles.
Lungs
Branching outTiny airways in the lungs are branching out, and the first air sacs are starting to form at their tips.
Nerves and face
Wiring upA protective coating called myelin is starting to form around your baby's nerves. Their eyes and ears are in position, and their lips and nose are taking shape.
Your morphology scan
The morphology scan, sometimes called the 20-week scan, is a detailed ultrasound usually done between 18 and 20 weeks. It's optional but offered to everyone, and it's often the first time you'll see your baby in so much detail.
- What it checks
- Your baby's growth and measurements, and a close look at their brain, face, spine, heart, stomach, kidneys, arms and legs.
- Around your baby
- Where the placenta is, how much amniotic fluid there is, and the umbilical cord.If your placenta is low-lying, you'll usually have another scan around 32 weeks, as it often moves up
- What to expect
- The scan is done on your tummy and takes around 30 to 60 minutes. If your baby isn't in a good position, you might be asked to walk around or come back to finish it.
Most scans show everything developing as expected. If anything needs a closer look, your doctor will talk you through it and any next steps.
Finding out the sex
If your baby is in a good position, the sonographer can often see their sex, though it isn't always certain. If you'd like it to be a surprise, let them know at the start of the scan. If you had NIPT, you may already know.
Symptoms at 18 weeks pregnant
You're almost halfway there, and your body is working hard. Here's what you might notice:
- A bigger appetite. Your body needs a little more energy now, about one extra healthy snack a day. Here's more on eating well in the second trimester.
- Back pain. Your growing bump shifts your centre of gravity. Wear flat, supportive shoes, bend your knees when lifting, and try a warm pack or gentle stretches.
- Leg cramps. Often at night. Stretch your calves before bed, stay hydrated and avoid sitting with your legs crossed.
- More discharge. Normal if it's milky and mild-smelling. Here's when to see your GP.
- Trouble sleeping. Discomfort, needing to wee and a busy mind can all keep you awake. A regular bedtime routine, less screen time before bed and a pillow between your knees can help.
Swelling: what's normal?
Around two-thirds of pregnant people notice some swelling, as your body holds more fluid and your growing uterus slows blood flow from your legs. It's usually harmless, but sometimes it can be a sign of something that needs urgent care.
Usually normal
- Mild swelling in your feet and ankles
- Rings feeling a bit tight
- Swelling that's worse at the end of the day and eases overnight
Get help urgently if
- Swelling comes on suddenly, or affects your face
- You have a bad headache or blurred vision
- You have pain under your ribs, especially on the right
- One leg is swollen, red, warm or painful
Resting with your feet up, staying active and drinking plenty of water can help ease everyday swelling.
Call your doctor, midwife or hospital straight away if you notice any of the urgent signs above. Go to your nearest emergency department if you have bleeding, strong pain or a gush of fluid from your vagina.
Keep moving
Unless your doctor has advised otherwise, regular exercise can help with back pain, swelling, sleep and mood, and it helps you prepare for labour. Talk to your doctor before exercising if you have a heart or lung condition, bleeding, a low-lying placenta, a history of premature labour, a stitch in your cervix, pre-eclampsia or you're expecting twins. Here are some great exercises for the second trimester.
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Helpful for this stage
Week 18 FAQs
What does the morphology scan check?
The morphology scan checks your baby's growth and looks closely at their brain, face, spine, heart, stomach, kidneys and limbs. It also checks the position of the placenta, the amount of amniotic fluid and the umbilical cord.
How long does the morphology scan take?
Usually 30 to 60 minutes. It can take longer if your baby isn't in a good position, and you may be asked to walk around or come back another day to finish it.
Can you find out the sex at 18 weeks?
Often, yes. The sex can usually be seen at the morphology scan if your baby is in a good position, though it's not always 100% certain. If you'd rather keep it a surprise, tell the sonographer at the start of your scan.
Is swelling normal at 18 weeks pregnant?
Mild swelling in your feet, ankles and fingers is common as your body holds more fluid. Get help urgently if swelling comes on suddenly, affects your face, or comes with a headache, blurred vision or pain under your ribs.
What if my scan shows a low-lying placenta?
A low-lying placenta is common at the morphology scan, and in most cases it moves up as your uterus grows. You'll usually have another scan around 32 weeks to check its position.
This article is general information and isn't a substitute for advice from your doctor or midwife.
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