20 Week Scan
Twenty weeks is NHS anomaly-scan territory: the most clinically detailed look most babies get during pregnancy. Here's what the NHS appointment screens for, how a private mid-pregnancy scan in Gosforth sits alongside it, and what we see on screen at the halfway mark.
Quick Answer
The NHS schedules its 20 week anomaly scan at this gestation, a specialised screening appointment that checks for 11 specific fetal conditions and is the diagnostic gold standard at this stage. Your baby is around 25cm long and roughly 300 grams, with every major organ formed. Most mums have felt definite movement by now. A private 20-week scan in Gosforth sits alongside (rather than instead of) the NHS appointment, with longer time, family-friendly seating, gender confirmation if you'd like it, photos and a relaxed setting. At our clinic a 20-week well-being scan is £65, or a Luxury Gender Reveal is £95.
What's Happening at 20 Weeks
Twenty weeks is the pregnancy halfway mark and a remarkable point of completeness. Your baby is roughly banana-sized, around 25 centimetres head-to-heel, weighing in at about 300 grams. Every major organ has formed; the work now is refining function rather than building new structure. The kidneys turn out around 7ml of urine an hour. The brain has all the neurons it will ever have, and those neurons are wiring themselves to each other at extraordinary pace. The pancreas has started producing insulin, the gallbladder is producing bile, and the digestive system is rehearsing by swallowing amniotic fluid.
Outwardly baby looks like a small, finished person. The skin has thickened from the translucent paper of earlier weeks and is now coated in vernix, the creamy white layer that protects baby's skin from the amniotic fluid right through to birth. Eyebrows and eyelashes are fully there. Fingernails have grown to the tips. The genitalia are unmistakable on ultrasound, which is part of why gender is so reliably identifiable at this point, whether on a standalone gender determination scan or as part of a celebratory luxury gender reveal package. If you're carrying a girl, her ovaries already hold millions of egg cells (a number that, paradoxically, will fall as she grows). If a boy, the testes have begun their slow descent from the abdomen, although they won't reach the scrotum until close to birth.
By twenty weeks most mums, even first-timers, can feel definite movement. Those early flutters at 17 or 18 weeks have firmed up into proper kicks and rolls. Baby is settling into sleep-wake cycles of around 20 to 40 minutes and starting to react to outside sounds. This is the gestation at which talking, singing or playing music to your bump genuinely registers on the other side.
The NHS Anomaly Scan: What It Checks
The NHS 20-week scan formally sits inside the Fetal Anomaly Screening Programme (FASP) and is designed to screen for 11 specific conditions. It runs 30–45 minutes, is delivered by sonographers with dedicated anomaly-screening training, and is the most thorough single look at fetal anatomy your baby will get across the pregnancy. There's no ambiguity: clinically, it's the gold standard at this stage.
The conditions on the screen list are anencephaly, open spina bifida, cleft lip, diaphragmatic hernia, gastroschisis, exomphalos, serious cardiac abnormalities, bilateral renal agenesis, lethal skeletal dysplasia, Edwards' syndrome (trisomy 18) and Patau syndrome (trisomy 13). Beyond that, the scan confirms placenta location (which matters for planning birth, a low-lying placenta may need follow-up monitoring), checks amniotic fluid volume, measures growth against the expected ranges, and reviews the umbilical cord.
If everything looks normal, the NHS sonographer will tell you so during the appointment. If something is flagged, you'll be referred to a fetal medicine specialist for further investigation, usually within one to three weeks. Whatever else you book privately, please don't skip the NHS appointment. Our NHS vs private comparison sets out the full case. It's the single most clinically important scan of the pregnancy.
Scan Packages for Week 20
Wellbeing & Reassurance Scan
From 15 weeks
A 15-minute reassurance check between NHS appointments. Heartbeat, position, growth, photos and digital images.
View package →Luxury Gender Reveal
From 15 weeks
If your NHS trust didn't disclose gender, a celebratory reveal package with confetti, sealed envelope option, gender card, photos and digital images.
View package →Book Your 20 Week Private Scan
Same-day or next-day slots often available at our Gosforth clinic. CQC-regulated, experienced and registered sonographers, two years on Bakers Yard, a fast-growing wall of five-star Google reviews since 2024.