One ultrasound before 24 weeks is a universal WHO recommendation for all pregnant women, even when you feel well.

What an early ultrasound shows

• Accurate dating. Ultrasound in the first half of pregnancy is the most accurate way to confirm how far along you are. This matters for testing windows, growth assessment, and decisions if pregnancy continues beyond 40 weeks
• Number of babies. Multiple pregnancy needs closer monitoring, so it is better to know early
• Baby's development. An anatomical scan can identify findings that may need monitoring or planning birth in a specialist centre
• Placental location

When to do it

WHO sets the upper limit at 24 weeks. In practice, scans are often done:

• At 11-14 weeks - first-trimester screening, dating, and basic anatomy
• At 18-22 weeks - detailed anatomical scan

Follow the schedule your healthcare provider recommends. The key point is to have an ultrasound before 24 weeks.

Is another ultrasound needed later?

If an early ultrasound has been done, WHO does not recommend routine scanning after 24 weeks because it has not been shown to improve outcomes. Your healthcare provider may still order a later scan for specific reasons, such as fetal position, growth, or placenta location. If no early ultrasound was done, a later scan can help clarify key information.

Is it safe?

Ultrasound has been used in obstetrics for more than 50 years. There is no evidence of harm when standard medical ultrasound is used appropriately.

Your healthcare provider will decide the timing and scope of scans.