16 Week Scan
The sweet spot for gender determination on ultrasound, and a relaxed mid-pregnancy reassurance window between the NHS dating scan and the anomaly scan.
Quick Answer
At a 16 week scan, baby's gender can be determined with 99%+ accuracy on ultrasound (provided baby is in a cooperative position). The fetus is around 12cm long and looks unmistakably human, with a recognisable face, all four limbs, and plenty of movement on screen. The placenta is fully functional, the heartbeat is strong and easy to detect, and many mothers will start to feel the first flutters of movement (quickening) around this time. At Numi Scan Gateshead, a 16-week Gender Baby Scan costs £68 or our Luxury Gender Reveal Baby Scan package is £95.
What's Happening at 16 Weeks
By 16 weeks your baby is roughly the size of an avocado, about 12cm from head to bottom and weighing around 100 grams. The growth pace has slowed slightly compared to the explosive first trimester, but development continues to refine. Baby's skin is paper-thin and translucent, with the network of blood vessels visible underneath. Lanugo, the fine downy hair that covers the body, has started to appear. Eyebrows and eyelashes are forming. The bones, which began as soft cartilage, are gradually hardening into the skeleton baby will be born with.
The senses are coming online. Baby can now hear muffled sounds from outside the womb (your voice, music, the rumble of traffic), and from this point onwards, hearing develops rapidly. The eyes can detect light through the fused eyelids, even though they won't open until around 28 weeks. The mouth can suck, the hands can grasp, and there's plenty of movement: kicking, rolling, hiccupping, sometimes even thumb-sucking. Most first-time mothers won't feel these movements yet (quickening typically arrives at 18–22 weeks for first pregnancies, earlier for subsequent ones), but you'll see plenty of action on the ultrasound screen.
The reproductive anatomy is now fully differentiated and clearly visible on a high-quality 2D ultrasound. This is why 16 weeks is widely considered the sweet spot for gender determination on a Gender Scan: the genital tubercle has formed unambiguously, but baby isn't yet so big that positioning becomes a problem (which can happen in the third trimester).
Gender Determination at 16 Weeks
The most common reason parents book a 16-week private scan is to find out whether they're having a boy or a girl, and 16 weeks is genuinely the right gestation for it. Earlier, at 12 weeks, the genital tubercle is forming but hasn't differentiated enough for confident identification (accuracy is only around 70–75% at 12 weeks, which most sonographers consider too low to call). By 15 weeks accuracy climbs to roughly 95%. By 16 weeks, with an experienced sonographer and a cooperative baby, accuracy is 99%+.
The dependency is baby's position. If baby is lying with legs crossed, sitting on their bottom, or has a hand strategically placed, the view of the genital area can be obscured. When this happens we'll usually try gentle repositioning techniques (asking you to walk around for a few minutes, having a sip of cold water, lying on your side) and if baby still won't cooperate we'll invite you back for a free recheck the following week.
If position-dependency feels too uncertain, our DNA-based Gender Blood Test from 8 weeks is an alternative: it's 99% accurate, doesn't depend on baby's position, and gives results from much earlier in pregnancy. Many parents who want absolute certainty at the earliest possible moment combine the DNA test with a Luxury Gender Reveal scan at 16 weeks for the visual confirmation.
Scan Packages for Week 16
Gender Baby Scan
From 15 weeks
Standard 20-minute gender confirmation scan with photos and digital images. The straightforward option.
View package →Luxury Gender Reveal Baby Scan
From 15 weeks
Extended scan with confetti cannon, sealed envelope option, gender card, photos and digital images. The full reveal experience.
View package →Early Gender Blood Test (DNA)
From 7 weeks
Lab-based DNA gender test, 99% accurate from 7 weeks. Position-independent, perfect alongside an ultrasound for absolute certainty. £125 blood test only, or £175 with an early pregnancy scan.
View package →Book Your 16 Week Scan
Same or next-day appointments often available. CQC-regulated, experienced and registered sonographers.
Frequently Asked Questions
Yes, at 16 weeks, gender can be determined on ultrasound with 99%+ accuracy in most cases. By 16 weeks the genital tubercle has fully differentiated and is clearly visible if baby is in a cooperative position. Occasionally baby is positioned in a way that hides the relevant anatomy (legs crossed, bottom-down, hand in the way), in which case we'll usually offer a complimentary recheck the following week. For earlier or more certain results, our DNA-based Gender Blood Test from 8 weeks is 99% accurate at any gestation from 8 weeks onwards.
They serve different purposes. The NHS 20-week anomaly scan is a specialised clinical screening scan run by sonographers trained specifically in detecting fetal abnormalities, and it's the diagnostic gold standard for that purpose. A private 16-week scan is a reassurance and gender-confirmation scan with a more relaxed atmosphere, more time, family welcome, and bonding photos. The 16-week private scan does not replace the 20-week NHS scan and we strongly recommend you keep your NHS appointment.
Some mothers do, particularly second-time mums. First-time mums often don't feel definite movement (called 'quickening') until 18–22 weeks. At 16 weeks baby is making lots of small movements (kicking, stretching, opening and closing hands), but they're often too subtle to feel through the abdominal wall. On ultrasound you'll likely see plenty of movement on screen even if you can't feel it yet.
On a high-quality 2D ultrasound performed by an experienced sonographer, gender determination at 16 weeks is around 99% accurate. The key dependency is baby's position: if the legs are crossed or baby is bottom-down, the view of the genital region can be obscured, and we'd rather wait or recheck than guess. For absolute certainty without dependency on baby's position, the Gender Blood Test (DNA-based, from 8 weeks) is also 99% accurate and isn't affected by how baby is lying.
Numi Scan Gateshead offers two 16-week options. Our standard Gender Baby Scan at £68 is a 20-minute appointment with gender confirmation, a heartbeat check, and 2D photos. Our Luxury Gender Reveal Baby Scan at £95 adds a confetti cannon, a sealed envelope option (so a friend or family member can be the first to know if you'd prefer), gender card, and extended scan time. Both include digital images by email.
Yes, this is a popular option with our Luxury Gender Reveal package. The sonographer notes the gender on a gender card, places it in a sealed envelope, and gives it to you to hand to a family member, baker, or party planner for a reveal at home. We don't tell you on the day if you'd prefer to find out later. It's particularly popular for parents organising gender reveal parties.
Yes, 16 weeks is too early for 4D HD Live bonding scans. At this stage baby has very little subcutaneous fat, so the 4D rendering looks gaunt and bony rather than the soft baby-face most parents are hoping for. Our 4D bonding scans are scheduled from 24 weeks onwards (peak window 24–34 weeks). See the 28-week milestone guide for the sweet spot when the rendered face looks photorealistic.