12 Week Scan
The end of the first trimester, and the week the NHS books most parents in for their dating scan. Here's what we see, how a private 12-week scan compares, and why many parents do both.
Quick Answer
A 12 week scan shows your baby fully formed in miniature: recognisable head, limbs, organs, often moving on screen. Crown-rump length is measured for accurate dating (within 3–5 days), the heartbeat is confirmed, and the placenta is located. The NHS schedules its dating scan at this gestation, usually combined with nuchal translucency screening for chromosomal conditions. A private 12-week scan complements (but doesn't replace) the NHS appointment with longer time, better imagery, family-friendly environment, and same-day availability. At Numi Scan Gateshead a 12-week scan costs £70.
What's Happening at 12 Weeks
By 12 weeks your baby is roughly the size of a lime, about 5 to 6 centimetres from crown to rump, weighing around 14 grams. The transformation from the small flickering bean seen on a 6-week scan is dramatic. Every major organ has formed and is now refining: the kidneys are starting to produce urine, the bone marrow is producing white blood cells, the intestines have moved from their early position in the umbilical cord into the abdomen, and the vocal cords are taking shape. The brain is developing rapidly, with neurons forming at a rate of nearly 250,000 per minute.
Externally, baby looks unmistakably human. Fingers and toes are fully separated and even have the beginnings of nails. The eyelids have formed and are fused shut (they won't open until around 28 weeks). The face has taken on its familiar profile, with a defined chin, nose and forehead. If your baby is in a cooperative position, you may see them moving on screen (kicking, stretching, or even hiccupping), though most mothers won't feel these movements yet for another few weeks.
This is also the gestation at which the NHS schedules its dating scan, and for good reason: it's the single most informative early pregnancy scan. Dates can be confirmed with high accuracy via crown-rump length measurement, the nuchal translucency screening test can be performed, anatomy is developed enough to spot most major abnormalities, and the chance of miscarriage from this point onwards has dropped dramatically.
The NHS Dating Scan vs a Private 12 Week Scan
The NHS dating scan is the foundation of antenatal care in the UK, and it's a thorough piece of clinical work. In a 15–20 minute appointment, your NHS sonographer measures crown-rump length to confirm dates, performs a nuchal translucency measurement (the fluid-filled space at the back of baby's neck) for combined-test screening of Down's, Edwards' and Patau syndromes, screens for major structural abnormalities, locates the placenta, and confirms whether you're carrying one baby or more. It is, clinically, the gold standard for this stage of pregnancy and we strongly recommend you keep your NHS appointment. See our private vs NHS comparison guide for the full context.
A private 12-week early pregnancy scan does some of the same things (confirms dates, checks for major anomalies, locates the placenta, sees the heartbeat), but in a different mode. Where the NHS appointment is focused and clinical, a private scan is longer (typically 25–30 minutes), more relaxed, and explicitly designed for parents to enjoy seeing their baby. You can bring partners, parents, and older children. The screen is angled so everyone can see. Photos and digital images are included in the price, not extras. And appointments are typically available within days, not weeks, so you can have your private scan as a 'preview' before the NHS appointment if you'd like.
The two scans answer different questions. The NHS scan answers "is this pregnancy clinically on track?" The private scan answers "what does my baby look like, can my family see, and can I have something to take home?" Done together, they cover the full picture, which is why most of the parents we see at this gestation aren't choosing between, they're booking both.
Scan Packages for Week 12
Early Pregnancy Scan
6–15 weeks
25-minute appointment with heartbeat confirmation, dating, and a full clinical check. Photos, digital images and written report included.
View package →NIPT Test
From 10 weeks (three tiers)
DNA-based screening for Down's, Edwards' and Patau syndromes, earlier and more accurate than the NHS combined test. Higher tiers add sex-chromosome and microdeletion conditions.
View package →Book Your 12 Week Scan
Same or next-day appointments often available. CQC-regulated, experienced and registered sonographers, a fast-growing wall of five-star reviews since 2024.