By the third trimester you have probably had a few scans already, but a growth scan has its own job: checking how your baby is doing as the due date gets closer.
It is sometimes called a wellbeing or reassurance scan, and for most parents that is exactly what it delivers: a chance to see your baby moving, stretching and growing well.
- Gel and positioning5 min
- Measurements15 min
- Fluid, placenta & movement12 min
- Findings and your plan8 min
View as table
| Part of the visit | Typical time |
|---|---|
| Gel and positioning | about 5 minutes |
| Measurements | about 15 minutes |
| Fluid, placenta & movement | about 12 minutes |
| Findings and your plan | about 8 minutes |
01What a growth scan is
A growth scan evaluates your baby’s development in the last trimester, usually performed between 24 and 40 weeks. It measures your baby’s size and checks their overall wellbeing, part of our private pregnancy ultrasound scan services.
It is not routinely offered on the NHS, but is often recommended if you have a history of premature delivery, gestational diabetes, or another factor that could affect growth. If you are not sure whether it applies to you, ask. Our team is happy to talk it through.
A growth scan is not a standalone diagnostic tool and will not detect every possible problem. It is best thought of as added reassurance, and a lovely opportunity to see your baby before they arrive.
02What to expect during the scan
You will lie down on an examination bed and a water-based gel is applied to your abdomen. It will not stain your clothing or skin. A small transducer is then moved across the gel to capture images of your baby, displayed on the screen as you watch.
The scan is performed externally and is entirely painless. Your sonographer may ask you to shift position or hold your breath briefly to get the clearest possible images. It usually takes around 30 to 45 minutes.
- The circumference of your baby’s head
- The circumference of your baby’s abdomen
- The length of your baby’s thigh bone (femur)
- The amount of amniotic fluid
- Your baby’s position and movements
- The position and maturity of the placenta
From these measurements, your sonographer estimates your baby’s weight and plots it on a growth chart against typical development for their age.
03The organs checked along the way
As well as size, a growth scan looks closely at some of your baby’s essential organs:
- Brain, the control centre for every other system, checked to confirm it is developing as expected.
- Heart, size, shape and rhythm, checked for anomalies.
- Diaphragm, the muscle behind breathing, checked for size and position.
- Stomach. Your baby’s first food processor, checked for size and position.
- Kidneys and bladder, part of the waste-removal system, checked for normal development and position.
Sometimes a more detailed look is needed, checking your baby’s limbs and the fluid spaces within the head, or using Doppler measurements to confirm healthy blood flow. We also look for a rare heart condition called an Ebstein anomaly, which can be difficult to detect until the third trimester.
04What the results might show
Most growth scans are reassuring: your baby is growing within the expected range, and no further monitoring is needed.
If your baby is measuring smaller than expected, this can be a sign of small for gestational age (SGA), which may be linked to the placenta or other factors. It is one of the reasons regular growth scans matter, as SGA can raise risks around pregnancy and birth. If your baby is measuring larger than expected, this may point to large for gestational age (LGA), which can be linked to hereditary factors, weight gain in pregnancy or gestational diabetes, and can affect delivery.
Every baby grows at their own pace, and there is real variation from week to week. Your specialist takes all of this into account, and will work with you on next steps if anything falls outside the average range.
05Getting your results
You will have your results at the end of the appointment. Your sonographer explains the images, the measurements and what they mean before you leave. A detailed written report follows, published to your secure patient portal, usually the same day.
Remember that images are a snapshot in time, and babies grow quickly in the third trimester, so measurements can shift between visits. That is not a cause for alarm; it is simply how growth scans work.
06What happens next
There is no special care needed afterwards. You can go straight back to your day. Depending on your results, your specialist may suggest a follow-up scan or, occasionally, further testing such as amniocentesis. For genetic screening earlier in pregnancy, a NIPT test is available from 10 weeks.
