Dating scan: the early pregnancy ultrasound

The dating scan is often the first time you’ll see your baby. It’s an early pregnancy ultrasound with a few important jobs.

What a dating scan checks

A dating scan is usually done between about 6 and 10 weeks of pregnancy.^[1] It:

• confirms the pregnancy is developing in the uterus (in the right place);
• checks for the heartbeat;
• sees whether there’s one baby or more (twins or more);
• measures the baby (the crown–rump length) to work out an accurate due date.

Getting the dates right early matters, because it sets the timing for later checks — including the 12-week scan and the 18–20 week morphology scan.

Why it’s often an internal scan

In early pregnancy the baby is tiny, so a transvaginal (internal) ultrasound often gives a much clearer view than scanning through the tummy — especially before about 8 weeks.^[2] This is your choice, and it shouldn’t be uncomfortable (see our transvaginal ultrasound guide). A little later, an abdominal scan (with a full bladder) may be enough.

What to expect

It uses sound waves — no radiation — and is safe for you and the baby.^[2] The scan takes about 15–30 minutes. It’s a medical scan, not a keepsake session, though many clinics will give you a printout.

A note on emotions: an early scan is usually reassuring, but occasionally it shows the pregnancy isn’t developing as hoped. The sonographer can’t always give results on the spot; your doctor or midwife will discuss anything that needs follow-up.

Frequently asked questions

When is a dating scan done?

Usually between about 6 and 10 weeks — early enough to confirm the pregnancy and set an accurate due date.^[1]

Why is the dating scan internal?

Because the baby is very small early on, a transvaginal (internal) scan gives a clearer view. It’s your choice, and an abdominal scan may be offered instead.^[2]

Is a dating scan safe?

Yes — it uses sound waves, not radiation, and is a routine, safe part of early pregnancy care.^[2]