Skull theory – can you really predict your baby’s sex?

We're not entirely convinced...but you might want to give it a try


Forget finding out your baby’s sex at the 20-week scan: for many people, the urge to know their baby’s sex as soon as they’re pregnant is so strong they’ll look at a wealth of theories and old wives’ tales to see if they can guess as soon as possible. And so, early scans become a source of scrutiny.


One such idea is to look for clues within the shape of your baby’s skull – looking at your 12 week scan pic. The second is to look at the the ‘angle of the dangle’ – the nub theory, which you can read all about here.

The basic premise of the skull theory is that men have squarer, stockier and bigger heads than women, and, so the theory goes, these differences may be spotted in the womb.

The hypothesis is based on comparisons of adult skulls, which have found the average key differences between men and women:

1. A man’s head is blockier and bigger than a woman’s head

2. The temporal ridge, which runs along the outer side of the top of the skull, is squarer on a man than a woman

3. The ridge above a woman’s eye sockets is sharp, while the man’s is rounder

4. Cheekbones are more pronounced on a male skull than a female one

5. The male skull has a square jawbone: the woman’s skull has a rounder one

6. The male forehead is lower and more sloping

Does it work?

Unfortunately the science on this one is more than a little shaky. For starters, the human skull continues to form and grow well beyond the womb.

Add to this the fact that skulls actually vary greatly between different racial groups too, as well as between the sexes – and the substance falls away from the argument pretty much altogether.

Kristina Killgrove, a bioarchaeologist at the University of West Florida says that, simply put, the theory makes no sense whatsoever.

‘Until you get to maturity or at least puberty you just don’t get these sexually dimorphic features of the skulls in males and females.’

In other words, while there may well be clear differences between a grown male and grown female skull, it’s very hard to see how these features could relate to an unborn baby.

What do our mums say?

There are certainly plenty of threads in our forums about skull theory – mainly comprising lots of mums posting up scan pictures and asking for advice on whether it’s a boy or a girl.

StaceyCheryl posted her scan photo up – with three mums guessing a boy and two mums guessing a girl…


A later 3D scan picture revealed…it was definitely a girl!

The MadeForMums verdict on skull theory

We definitely wouldn’t be making any bets based on this theory, but it’s pretty fun trying to work it out.

Yep, on the whole we reckon when it comes to getting the sex right with this one, it’s pretty much 50/50. Who’d have guessed?

Read more


Images at the top show a boy skull (left) and a girl skull (right)

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