Skull theory explained: Predict your baby’s sex using your 12-week scan photo

Skull theory explained: We take a closer look at the skull theory – a fun method that some claim can determine your baby’s gender with just your 12 week scan!

Waiting 20 weeks to find out the gender of a baby can be torturous for some parents. Likewise friends and family normally can’t resist guessing at the baby’s gender either – so many turn to other methods during those first weeks of pregnancy to try and work out if they’ll be welcoming a boy or girl.

Like the nub theory (which looks at the direction the genital tubercle is pointing), or the Chinese birth chart (which uses the mother’s age and the month of conception to guess a baby’s sex) the skull theory is another fun method of try to predict your baby’s gender.

What is skull theory?

The skull theory is centred on an analysis of the cranial differences between men and women.

Those who back the theory believe that such distinctions are visible in the womb.

This means that it might be possible to decipher whether a little one is male or female by studying the black and white 12-week scan photo.

While it’s not something with any scientific backing, it’s been reported by Netmums that this sex determination technique carries an accuracy rating of 92%.

Skull theory is popular among users on parenting forums who share pictures of their scans before asking other members to guess the gender of the unborn child.

Skull theory scan pic

How do male and female skulls differ?

Keen to put the skull theory to the test? Grab your scan and see if you can spot any of the differences between male and female skulls that we outline below.

In terms of weight, male skulls tend to be heavier than those of females. The bones in a man’s skull are said to be thicker too.

When it comes to the foreheads, ones belonging to males are lower and more sloping. A lady’s forehead is more vertical.

A comparison of the brow ridge – formally referred to as the supraorbital margin – also yields an interesting observation. For men, this area is curved while for women, it’s sharper in appearance.

Below the lower eye ridge is the zygomatic bone. More commonly known as the cheekbone, this tends to be more pronounced on the skull of a male. The same can be said of the superciliary arch, the ridge on the frontal bone above the eye sockets.

Another structural difference can be seen at the lower jawbone – a man’s is squared, while a woman’s has a rounded appearance.

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It’s also worth taking a look at the gonion, the point where the bottom of the lower jaw curves upward toward the ear. If it appears to be flared out or sharply angled on the scan, this might be an indicator that you’re expecting a boy.

Have you tried the skull theory? Was the prediction correct for you in the end? Let us and other mums know your findings in the comments below!