If you've been booked for a growth scan later in pregnancy, you might wonder why, especially if everything has gone smoothly so far. Here's what a third-trimester growth scan is and why it's valuable.
What a Growth Scan Is
A growth scan is an ultrasound, usually done in the third trimester (after 28 weeks), that measures your baby to check they're growing well. The sonographer measures:
- The head circumference
- The abdominal circumference
- The thigh bone (femur) length
These are combined into an estimated fetal weight and plotted on a growth chart to see how your baby is tracking.
More Reasons Why Growth Scans Are Ordered
- Your bump is measuring larger or smaller than expected on examination
- You have a condition like gestational diabetes or high blood pressure
- There's a history of a small or large baby in a previous pregnancy
- You're expecting twins or more
- There are concerns about the placenta or reduced baby movements
- A previous scan flagged something to recheck
What the Scan Also Checks
Beyond size, a growth scan often assesses:
- The amount of amniotic fluid
- The position of the baby and the placenta location.
- Blood flow through the umbilical cord and placenta (Doppler), which shows how well the baby is being nourished by the placenta.
Why "Trend" Matters More Than One Number
A single measurement is less important than the pattern of growth over time. Your care team looks at whether the baby is following its own steady curve. This is why growth scans are sometimes repeated a few weeks apart.
What Happens With the Results
Most growth scans are reassuring. If a scan suggests the baby is growing too slowly, too quickly, or that fluid or blood flow needs watching, your team may arrange closer monitoring or discuss timing and mode of delivery — always with your wellbeing and the baby's at the centre.
This article is for general information and is not a substitute for advice from your midwife or obstetrician.
Ready to Book Your Growth Scan?
Mascot Healthcare Clinic, Akoka (Yaba), Lagos offers ultrasound scans by appointment only, Monday–Saturday, 9am–5pm. Book online and choose a time that works for you.