Are you looking for a baby gender scan? Are you 11 weeks or over? If the answer is yes, read on ! 

When Can I Have My Baby Gender Scan and Early Growth/Wellbeing Scan?

  • There is an optimal time to achieve the highest accuracy in determining gender of your baby and get great scan pictures as a memory of that first moment you discovered your unborn baby’s gender.
  • A pregnancy gender scan cannot be carried out before 11 weeks. It is not possible to accurately scan and assess fetal gender before 11 weeks so gender assessment cannot done at the Viability (6 -10+ week) scan.
  • From 11-13+ weeks range, the gender can be  assessed by the angle of the genital tubercle (nub) relative to the spine. Genitalia in boys and girls develop from the same embryonic space.
  • It is possible to assess the gender of your baby when you come for a Nuchal Scan between 11 and 13+ weeks if you wish. The accuracy rises rapidly from the bottom end of the 11th week (75%) to the upper end of the 13th week (95%).
  • At 11 weeks –  75% accuracy. If you got this in an examination would be a pretty good percentage, but not when you want to know the gender of your baby! It means that on 25 occasions out of 100 scans, the gender of the baby will be wrong.

So at this stage, patience is the key.

  • At 12 weeks – accuracy goes up to 80-90%
  • At 13 weeks – accuracy is at 95%
  • The best time to have a Nuchal scan assessment is between 12 ½ weeks and 13 ½ weeks (so you can have the nuchal scan at the same time as the early growth scan)
  • At 14/15 weeks – accuracy 97%
  • At 16 weeks  – accuracy is 99.9% – this means that 1 in 1000 assessments will be wrong.

How Can You Tell If I Am Having A Boy or A Girl When My Baby Is So Small?

At 12 weeks, the fetus is about 50mm (<2”) CRL (crown/ rump length – head to butt) and that is little more than the width of two 2pence coins! The nub at this gestation is about the size of a ‘pin head’! (If you would like to know more about the nub theory click on the link)

Looking on ultrasound scan, Mr Penman is looking for two signs:

  • One is a ‘snail’ sign, which will show him that your baby is a boy.
  • The other is a ‘Big Mac’ sign which will indicated that your baby is a girl. However the absence of a penis cannot be taken as evidence that the fetus is a girl. But the ‘Big Mac’ denotes the lines of the labia are a very valid and accurate indication the fetus is a girl.

The Scan

Mr Penman will perform a thorough scan checking your baby’s wellbeing and growth, taking pictures and 4D movie at the same time. He will also perform the gender assessment. This will all be recorded in a wellbeing report for you and your doctor/midwife and all your image and movie will be saved onto a USB for you to take away.
The accuracy of the scan even at this gestation is still dependent on fetal position, amniotic fluid volume and maternal obesity (BMI).

Booking A Scan 


If you would like to book a scan please click on the the link here to the booking page or click on the big blue button to the right of this article. You can submit an online booking form for an appointment at the Spire Alexandra Hospital.