Guess the Sex of your Baby at 12 Weeks!

Guess the Sex of your Baby at 12 Weeks!

Going for your first pregnancy scan is such a special moment. Once you have had the scan and got the picture in your hand, you may be looking for any clues as to what the sex of the baby might be so that you could begin decorating the nursery and buying clothing.

But since your first scan is at 12 weeks, there's surely no way of you finding out until at least 20 weeks when the foetus is developed enough to determine the sex.

Or is there? There is this phenomenon called the nub theory, which some people use to predict the sex of the baby using clues on the scan- here we discuss it in detail to give you an idea of how accurate it could be and how it works.

Article Contents


What is the nub theory?

There are lots of old-wives’ tales about telling the sex of your baby. Such as if you have a low baby bump, it means it is a boy, or if you crave sweet things, it's a girl. But now, the nub theory is becoming an ever more popular way of guessing whether your baby is going to be a girl or a boy.

The nub theory claims to be more accurate than any of the old wives’ tales. Many believe using the nub theory with your 12 week scan means you can find out a little earlier than you could via medical means.

It is around your first scan, 11-13 weeks of pregnancy, that babies have what is known as a 'nub' between their legs. The real name of this 'nub' is the genital tubercle and how the nub theory works is the angle of the nub can reveal whether you will be having a girl or a boy. If the nub is over 30 degrees up from the spine, then it is believed that the baby would be a boy, and if it is under 30 degrees, then your baby could be believed to be a girl.

This theory, along with others such as the skull theory are being a lot more popular rather than waiting for the 20-week scan – let’s face it, many of us are impatient about finding out the sex of the baby.

The skull theory is also believed to be very accurate, some say up to 92 per cent accurate, and this also uses your 12-week scan and looks at the shape of the skull on your scan picture. So, they may both be worth a try if you cannot wait to find out what you’re having!


Your first scan

All women who are pregnant are offered to attend a 12 week scan, however this can be any time from 8-14 weeks that you get your scan date. This is the dating scan where the sonographer will take measurements of your baby, and this calculates an accurate due date when your baby is expected to arrive. 

Like the other methods of guessing the gender of your baby we mentioned earlier, the nub theory does not have enough hard evidence to say looking at the 'nub' will give you the correct sex of the baby.

Some sonographers are more unreliable and get it wrong throughout the pregnancy, and there's been mums and dads confused at the delivery with all their pink clothes and a boy arrives, However, this is very rare. However, The Nub theory has been said to be relatively accurate. According to Netmums, the accuracy statistics are:

  • At 11 weeks – 48 percent accuracy
  • At 12 weeks – 91 percent accuracy
  • At 13 weeks – 94 percent accuracy


Can the nub theory be wrong? 

Whether you use the nub theory, look at the position of your bump or track what your cravings are no matter what way you try and guess the sex of your baby it is never going to be 100% accurate, something may by chance be right and some might be wrong.

If when you go for your 12-week scan, your baby is very good, lying in the correct position on their side and the sonographer gets a good shot of your baby, you could have a better chance of the nub being clearly defined and giving more accurate results. 

However, the baby may not be laying in the right position, and the sonographer could get a picture of your scan at a different angle that shows the nub differently. These could give you the wrong prediction when looking at the nub theory.

The baby may be developing a little slower, the tubercle may not have started to point up, or the umbilical cord could be mistaken for a penis. All of these factors could give you the wrong prediction and could result in you spending money on the wrong colour theme for the nursery or clothing. 


Nub theory girl

This photo has an arrow showing the nub which is not pointing up more than 30 degrees; it is, in fact, almost horizontal. With the findings on this scan picture, you would predict this is a girl. 

Nub theory boy

This scan photo is showing a nub which is at a much steeper angle pointing upwards from the spine, indicating that this is going to be a baby boy.

Come back and tell us if you were right

Now you know more about how this theory works and how to look at your scan with using nub theory in mind to get an idea of the sex of your baby. It is definitely worth giving it a go.

If you are going for a scan soon, and are hoping to use the nub theory and predict the gender, we would love to hear from you in our comments section what your predictions could be.  Also pop back and tell us if this worked for you!

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