Third Trimester Growth Scan
Growth assessment in the final stage of your pregnancy — checking baby's size, position, and key measurements as you approach your due date.
About This Scan
A third trimester growth scan is performed between 25 and 40 weeks of pregnancy to check your baby's size, growth, and position as you approach delivery.
This scan provides important information about your baby's estimated weight, position (head down or breech), placental location, and amniotic fluid levels — all factors that become increasingly important as birth approaches.
Understanding the Results
Estimated Fetal Weight
Your baby's estimated weight is compared to other babies at the same gestation:
- 50th percentile: Average-sized baby
- Below 10th percentile: Smaller than average
- Above 90th percentile: Larger than average
Note: There is a recognised ±15% margin of error with estimated fetal weight. Your baby could be 15% smaller or larger than estimated. Despite this, ultrasound is the standard method used to assess your baby's size.
Amniotic Fluid
The amniotic fluid index (AFI) measures the fluid around your baby. Both too much (polyhydramnios) and too little (oligohydramnios) may require monitoring, though small variations are often normal.
Placental Position
We check that the placenta is not lying too close to the cervix (placenta praevia), which can affect delivery plans.
What You'll See
At this late stage, you'll see your baby in wonderful detail — their profile, face, hands, and feet. However, as babies grow larger, it becomes harder to see the whole body at once. The sonographer will focus on one part at a time.
Factors affecting image quality: Baby's position, amount of amniotic fluid, maternal body habitus. The sonographer will do their best to capture beautiful images, but please understand that late pregnancy scans can sometimes be challenging.
What We Check
- Head circumference (HC) and biparietal diameter (BPD)
- Abdominal circumference (AC)
- Femur length (FL — thigh bone)
- Estimated fetal weight (EFW)
- Baby's position (Cephalic, Breech, Transverse, or Oblique)
- Fetal heartbeat and heart rate
- Amniotic fluid levels (AFI)
- Placental position (checking for placenta praevia)
- Basic anatomy review (kidneys, bladder, face)
- Fetal movements
What's Included
- Growth measurements
- Estimated fetal weight calculation
- Position and presentation assessment
- Growth report
- Glossy keepsake photo
Why You Might Need This Scan
- •Growth monitoring: Tracking baby's growth measurements
- •Low-lying placenta: Follow-up if an earlier scan showed placenta praevia
- •Reduced movements: Assessing baby if movements have decreased
- •Baby's position: To confirm if baby is head down or breech
- •Additional information: Wanting to know baby's measurements and position
What to Expect
Before Your Scan
No special preparation is required.
Preparation checklist:
- Know your due date
- Wear comfortable, loose clothing
- Arrive a few minutes early
During the Scan
You'll lie comfortably on an examination table. The sonographer applies warm gel to your abdomen and moves the probe to visualise your baby.
You'll see your baby on a large screen. At this stage, baby fills most of the uterus, so you'll see detailed views of individual body parts — their face, hands, feet, and movements.
The sonographer will take measurements and check baby's position, placenta, and fluid levels. They'll explain what they're seeing throughout.
The scan typically takes 20-30 minutes.
After Your Scan
You'll receive immediate verbal results explaining your baby's growth, position, and estimated weight. You'll also receive a detailed medical obstetric report and a keepsake photo.
Pricing
Third Trimester Growth Scan: €150
Twins: +€100
Cancellation: We require 24 hours notice for cancellations or rescheduling.
Frequently Asked Questions
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Available 7 days a week across our three Dublin locations.
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Our experienced team is available 7 days a week across our three Dublin locations.