28 Week Scan
The third trimester begins, and the 4D HD Live bonding window opens. Baby's face is fully formed, eyes can blink, and there's still plenty of room to move. The single best window for keepsake imagery.
Quick Answer
At 28 weeks, baby is roughly 38cm long and weighs around 1kg. The face is fully formed with subcutaneous fat for soft features, eyes can open and blink for the first time, the brain is developing rapidly, and lungs are practising breathing motions. This is the sweet spot of the 24–34 week 4D HD Live window: baby has filled out enough for photorealistic facial features but isn't yet so cramped that getting a clear view becomes difficult. At Numi Scan Gateshead, our 4D Baby Scan is £78 and the Luxury 4D Baby Scan is now £135 (reduced from £145).
What's Happening at 28 Weeks
Twenty-eight weeks is the official start of the third trimester and a developmental turning point. Your baby is roughly the size of an aubergine, around 38 centimetres from head to heel, weighing approximately 1 kilogram. The dramatic structural development of the first two trimesters is essentially complete. From here onwards, the work is mostly growth, lung maturation, and the deep brain development that will continue for years after birth.
This is also the week the eyes open for the first time. Until 28 weeks the eyelids have been fused shut, protecting the developing retinas. Now they're physically capable of opening and closing, and baby will spend much of the third trimester practising: blinking, focusing on the dim light that filters through your abdominal wall, even responding to bright torches held against your bump. The lungs are producing surfactant, the substance that allows the alveoli to inflate and deflate properly after birth, and baby is making practice breathing motions even though there's no actual air to breathe yet.
Externally, baby has filled out beautifully. Where 20-week babies looked thin and slightly bony, 28-week babies are soft and rounded, with enough subcutaneous fat to give the face the kind of cherubic appearance most parents hope to see. The brain is developing folds and grooves at a tremendous rate, and the hair on the head is now usually visible on a 4D scan. Most mothers can feel strong, regular movement by now: kicks, stretches, hiccups, and the unmistakable rhythm of baby's sleep-wake cycle.
Why 28 Weeks Is the 4D Sweet Spot
4D HD Live bonding scans depend on three factors lining up: subcutaneous fat (so baby's face has soft, recognisable features rather than looking gaunt), amniotic fluid volume (so we have a clear acoustic window between the probe and baby's face), and room to manoeuvre (so we can find a position where baby's face isn't pressed against the placenta or the spine). All three factors are at their best between 24 and 34 weeks, and 28 weeks sits right in the middle.
Earlier, at 22 or 23 weeks, there isn't enough fat under the skin yet, so the rendered face looks gaunt and bony. The 4D imagery technically works but doesn't deliver the soft baby-face most parents are picturing. Later, at 35 or 36 weeks, there's plenty of fat, but baby is now so big that there's less amniotic fluid and less room to find a good face-up position. Many third-trimester babies spend this period with their face pressed against the placenta or with hands and feet in front of the face.
If you can only book one 4D scan, 28 weeks is the gestation we'd recommend. If you'd like the most flexibility, booking with the understanding that you can rebook within the 24–34 week window if baby isn't cooperative is the right approach, and our policy is to never charge twice for a scan where baby's position prevented us getting clear imagery first time round. For the standard 30-minute experience choose the 4D Baby Scan; for an extended 45-minute keepsake package the Luxury 4D Baby Scan is the upgrade.
Scan Packages for Week 28
4D Baby Scan
24–34 weeks
30-minute 4D HD Live appointment. Photos, digital images, USB and written report included.
View package →Luxury 4D Baby Scan
24–34 weeks
Extended 45-minute scan with the full keepsake package: multiple prints, USB with session recording, premium photo formats.
View package →Growth & Presentation Scan
From 24 weeks
Detailed clinical scan with full growth measurements, baby's position, fluid level, placenta location: the 2D late-pregnancy reassurance option alongside (or instead of) a 4D scan.
View package →Book Your 28 Week 4D Scan
The single best window for 4D HD Live bonding imagery. CQC-regulated, experienced and registered sonographers, latest GE Voluson Expert HD Live equipment.