Skull theory: can you predict your baby’s sex early at 12 weeks?

Baby scan photo

by Emily Gilbert |
Updated on

As soon as you announce that you're pregnant, talks soon turn to what your baby's sex will be. There are dozens of old wives' tales that try to predict your baby's sex, yet many mums swear by the technique known as the 'skull theory'.

Expecting mamas have been uploading their 12-week scan photos to try and get the internet to guess if they're having a boy or a girl. This quick analysis helps parents prepare for their new baby's arrival and start designing their nursery with a colour theme. For those who choose not to find out the gender of their baby, consider designing a gender-neutral nursery.

Traditional medical scans won't determine whether a baby is male or female until 20 weeks - but some experts think it is possible to predict the foetus' sex when you are 12 weeks pregnant.

What is skull theory?

First, you'll need your 12-week ultrasound picture to take a closer look at it. The idea is that girls have a different skull shape to boys. Boys predominantly have squarer chins, a chunkier skull shape and a more pronounced brow ridge, whereas girls’ skulls have a smaller brow ridge and more pointed chins.

Another method you may want to also try to confirm their suspected sex is the ‘nub theory’ which required you to take a closer look at the area between the legs. Babies with a ‘nub’ – or genital tubercle – angled at greater than 30 degrees are likely to be boys, while girls' nubs sit below 30 degrees.

How accurate is the skull theory

Some experts claim up to 88 per cent accuracy using the technique - making it more effective than the 75 per cent of parents who said their 20-week scan correctly predicted their baby’s sex. However, if we're being realistic, there is no scientific evidence to support the skull theory's accuracy and the skull differences to determine sex tend to only be visible in adult skulls, not neonatal ones, making the theory a little pointless.

Another popular theory that has gained popularity as a method for predicting a baby's sex is the Ramzi Theory. This gender-predicting method has been claimed by users to be 97% accurate and is based on the location of the placenta in the first ultrasound during the 6-week scan. However, this theory is also yet to be proven scientifically so do take it with a pinch of salt.

"The Nub and Skull theory is the fastest-growing gender prediction technique simply because it’s so social," says gender expert Lisa Lum.

"Three-quarters of mums who try it say they like getting other people’s opinions on their child’s sex while 30 per cent see it as a worldwide craze they like to be part of.

"While no non-medical technique is 100 per cent accurate, it’s fun and brings people together, which is exactly what children should do at all ages."

Try out skull theory

Can you use the skull theory to try and guess whether Candace is having a boy or girl?

Candace gave birth to a boy! Did you guess right?

Mum Rhiannon also shared her scan picture below - can you guess what she had?

Rhiannon gave birth to a beautiful baby girl!

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