30/05/2026
Why 36–37 weeks is considered optimal time for a presentation scan?
By this stage:
* Most babies have settled into their final birth position.
* A breech or transverse position can be identified reliably.
* There is still enough time to offer an External Cephalic Version (ECV) — a procedure that attempts to turn a breech baby head-down before labour.
The RCOG states that if a baby remains breech at 36 weeks, healthcare professionals should discuss options including ECV, planned caesarean birth, or vaginal breech birth.
Why not earlier?
A scan at 32–34 weeks can identify position, but many babies are still turning naturally at that stage.
RCOG notes that breech presentation is common earlier in pregnancy and that most babies will naturally move into a head-down position by 36–37 weeks.
If you scan too early:
* You may identify a breech baby that would have turned naturally.
* Findings may create unnecessary anxiety.
* Delivery planning decisions may need repeating later.
Why not leave it until 39–40 weeks?
A later scan can still confirm presentation, but it leaves less time for:
* ECV attempts
* Birth planning
* Specialist consultations if the baby remains breech
Clinical reviews evaluating routine late-pregnancy ultrasound generally focus on 35+0 to 36+6 weeks, supporting this window as the most useful balance between diagnostic accuracy and clinical action.