The Short Answer
The first routine ultrasound — called the dating scan or first trimester scan — is typically performed between 8 and 14 weeks of pregnancy, most commonly around 11–13 weeks. This scan confirms the pregnancy, establishes gestational age, and screens for chromosomal conditions.
Types of First Ultrasound Scans
Dating Scan (8–14 Weeks)
The most common first scan. Its main purposes are to:
- Confirm the pregnancy is in the uterus (not ectopic)
- Measure the embryo or foetus to estimate a due date
- Check for a heartbeat
- Confirm the number of embryos (identify twins or multiples)
Early Viability Scan (6–8 Weeks)
Offered when there is bleeding, pain, or a history of miscarriage. At 6 weeks, a heartbeat may be visible, a strong indicator of a viable pregnancy. This scan is usually transvaginal.
Nuchal Translucency Scan (11–14 Weeks)
Often performed alongside the dating scan. Measures fluid at the back of the baby's neck (nuchal translucency) as part of combined screening for Down syndrome (trisomy 21), Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13). Results are combined with blood tests (PAPP-A and free beta-hCG) for a risk estimate.
What the First Ultrasound Checks
- Heartbeat: Visible from around 6 weeks; strongly reassuring at 8–10 weeks (150–180 bpm is normal)
- Crown-rump length (CRL): Measurement from head to tailbone to calculate gestational age and due date
- Number of embryos: Identifies twins, triplets, or more
- Location: Confirms intrauterine pregnancy (rules out ectopic pregnancy)
- Placenta position: Early assessment
- Uterus and ovaries: Checks for fibroids, ovarian cysts, or other issues
What to Expect During the Scan
- Duration: 15–30 minutes
- Transabdominal scan: Gel on the abdomen, probe moved gently across the skin. A full bladder helps image quality in early pregnancy (many clinics ask you to drink water beforehand).
- Transvaginal scan: A small probe is gently inserted for clearer images, especially before 10 weeks when the uterus is still low in the pelvis. This is safe and normal.
Most scans produce still images or short video clips that you can take home.
How Accurate Is the Dating Scan?
A dating scan performed at 11–13 weeks is accurate to within ±5 days for estimating gestational age, according to the Society of Obstetricians and Gynaecologists of Canada (SOGC). This is more accurate than period-based calculations, especially for women with irregular cycles.
When Should You Book?
Most guidelines recommend booking your first antenatal appointment (booking appointment) at 8–10 weeks, so the dating scan can be scheduled in time for combined first-trimester screening at 11–13 weeks.
If you are unsure of your dates, are experiencing pain or bleeding, or have had a previous ectopic pregnancy or miscarriage, ask your provider about an earlier viability scan.
Country-Specific Schedules
| Country | Routine First Scan |
|---|---|
| UK (NHS) | 8–14 weeks (dating scan) |
| USA | Variable; often 10–13 weeks |
| Australia | 11–13 weeks (dating + NT scan) |
| Norway | 17–19 weeks (standard); 11–14 weeks on request |
Frequently Asked Questions
When is the first ultrasound during pregnancy?
The first routine ultrasound — called the dating scan — is typically performed between 8 and 14 weeks of pregnancy, most commonly at 11–13 weeks. This scan confirms the pregnancy, establishes gestational age, checks for a heartbeat, and identifies twins or multiples.
What does the first ultrasound check for?
The dating scan checks: that the pregnancy is in the uterus (not ectopic), the heartbeat (visible from around 6 weeks), crown-rump length to estimate due date, number of embryos, and early placenta position. The nuchal translucency scan, often combined with the dating scan at 11–14 weeks, screens for Down syndrome, Edwards syndrome, and Patau syndrome.
What is the difference between a dating scan and an anatomy scan?
The dating scan (11–13 weeks) establishes gestational age, confirms viability, and provides first-trimester screening. The anatomy scan (typically 18–22 weeks) is a detailed structural examination of the baby's organs, limbs, spine, and face. Both are routine scans, but they serve different purposes.
How accurate is the dating scan for predicting a due date?
A dating scan performed at 11–13 weeks is accurate to within ±5 days for estimating gestational age, according to the Society of Obstetricians and Gynaecologists of Canada (SOGC). This is more accurate than period-based calculations, particularly for people with irregular cycles. If your scan date differs from your calculated date, the scan date is generally used.
Do I need a full bladder for the first ultrasound?
For a transabdominal scan (probe on the abdomen), a moderately full bladder improves image quality in early pregnancy. Most clinics ask you to drink water in the hour before. For a transvaginal scan (small probe inserted internally) — which is common before 10 weeks — a full bladder is not needed and you may be asked to empty it beforehand.
When should I book my first antenatal appointment?
Book your first antenatal (booking) appointment at around 8–10 weeks of pregnancy so the dating scan can be scheduled in time for combined first-trimester screening at 11–13 weeks. If you have had bleeding, pain, or a previous ectopic pregnancy or miscarriage, ask about an early viability scan at 6–8 weeks.
What can be seen on an ultrasound at 6 weeks?
At 6 weeks, a transvaginal scan can usually detect the gestational sac and possibly a fetal heartbeat — though this is not always visible at exactly 6 weeks. The embryo at this stage is approximately 5–6 mm. A repeat scan at 8–10 weeks provides much clearer and more reliable information.
Key Sources
- NHS. Your Antenatal Appointments
- ACOG. Ultrasound in Pregnancy
- SOGC. Determination of Gestational Age by Ultrasound
Sources
- ACOG — Clinical guidance on pregnancy and women's health
- WHO — Global recommendations for maternal health
- Mayo Clinic — Evidence-based pregnancy health information
🔧 Helpful Tools
- Due Date Calculator — Calculate your estimated due date
- Contraction Timer — Track your contractions during labor
- All Baby Tools — Browse all free tools for pregnancy and baby care
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