Pregnancy Scan Timeline: Complete UK Guide
Knowing when each scan happens — and what it's checking for — can make antenatal care feel far less confusing. Here's the full UK timeline, from your booking appointment through to your last routine scan.
NHS Routine Scans
Most straightforward pregnancies in the UK involve two scheduled ultrasound scans, both free on the NHS.
- 12-week (dating) scan, between 11 weeks 2 days and 14 weeks 1 day: confirms your due date, checks the pregnancy is developing in the uterus, confirms how many babies you're expecting, and — if you opt in — includes NT measurement as part of combined screening.
- 20-week (anomaly) scan, between 18 and 21 weeks: a detailed check of your baby's organs, spine, brain, heart, and overall growth, along with checking the position of your placenta.
- Both scans are offered to everyone as standard NHS antenatal care, regardless of risk factors, and both are entirely optional if you choose to decline them.
Blood Tests Alongside Scans
Scans are only part of the picture — several blood tests happen at set points too.
- Booking appointment bloods (ideally by 10 weeks): blood group and rhesus status, screening for anaemia, and screening for infections such as HIV, hepatitis B, and syphilis.
- Combined screening bloods (11-14 weeks): taken alongside the 12-week scan to combine with your NT measurement for a chromosomal condition chance score.
- Glucose tolerance test (24-28 weeks): offered if you have risk factors for gestational diabetes, such as a higher BMI, a family history of diabetes, or a previous large baby.
- Additional bloods, such as further anaemia checks around 28 weeks, are also routine for most pregnancies.
Additional and Private Scans
Beyond the two NHS routine scans, some women have extra scans for medical or personal reasons.
- Early/reassurance scans (from around 6-9 weeks): often privately booked, particularly after previous loss or if there's early bleeding or pain.
- Growth scans (any point from around 28 weeks onward): offered on the NHS if there are concerns about your baby's growth, or available privately for reassurance.
- Gender scans (typically from 16 weeks): usually private, as the NHS doesn't guarantee revealing sex, though it's often visible at the 20-week scan if the baby is well positioned.
- 4D/HD scans (usually 26-32 weeks): private, non-medical scans offering a more detailed 3D-style image, purely optional.
Frequently Asked Questions
When are NHS pregnancy scans?
There are two routine NHS scans: the 12-week (dating) scan between 11 weeks 2 days and 14 weeks 1 day, and the 20-week (anomaly) scan between 18 and 21 weeks. Some women have additional scans for medical reasons, such as monitoring growth or twins, and all clinically necessary scans are free on the NHS.
Can I have extra scans privately?
Yes — many parents book private scans for reasons the NHS timeline doesn't cover, such as early reassurance before 11 weeks, a dedicated gender reveal scan, or a 4D scan later in pregnancy. These sit alongside, not instead of, your NHS scans, and prices and availability vary by clinic.
What if I miss the window for the 12-week scan?
If you book your pregnancy late or have a longer cycle than average, your midwife will still arrange your dating scan as close to the ideal window as possible — sometimes it happens slightly outside 11-14 weeks. Combined screening (which includes NT measurement) has a strict cut-off, so if you're near the edge of the window, it's worth contacting your midwifery team promptly to check your options.
This article is for informational purposes only and does not constitute medical advice.
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