Nub theory explained: Predict your baby’s sex at 12 weeks

Nub theory - have you heard of it? It can help you find out if your baby is a boy or girl from just 12 weeks.
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  • What exactly is the nub theory - and how can it help to predict the sex of your baby before the five month scan?

    We’ve all heard of the old wives tales like carrying your baby bump low means it’s a boy, or if you’re craving sweet things, you’re expecting a girl.

    If you’re looking for the nub theory explained, or want some more ideas on how to tell your little one’s gender, you’ve come to the right place.

    The nub theory claims to be a lot more accurate than some of those old wives tales – and claims you can even tell the sex of your baby just by looking at your 12 week ultrasound picture. Usually the earliest point you can tell the sex of a baby from a scan is 20 weeks, so the quirky theory is popular with those who can’t wait to find out if they’re having a little girl or boy.

    What is nub theory?

    Between 11-13 weeks, all babies are said to have a ‘nub’ between their legs called the genital tubercle, and according to this theory the angle of the nub will indicate whether it’s a boy or girl.

    It’s said that if the nub is over 30 degrees up from the spine, it’s a boy – but if it’s under that then it’s a girl.

    Confused? See our pictures below as an example.

    Nub theory indicating a girl

    Nub theory - girl picture
    The nub isn’t pointing up more than 30 degrees from the baby’s spine – in fact it’s almost horizontal – so believers would say this showed the scan to be a little girl.

    Nub theory indicating a boy

    Nub theory - boy picture
    The nub is at a much steeper angle upwards from the spine, indicating that this could be a baby boy.

    Not convinced? Netmums have reported the following statistics inline with the nub theory:

    • At 11 weeks, the accuracy rate is 48 per cent
    • At 12 weeks, the accuracy rate is 91 per cent
    • At 13 weeks, the accuracy rate is 94 per cent

    Going for your scan soon? You’ll have to hope for co-operation from your baby as some professionals say the accuracy actually all depends on the angle of the baby.

    If you can get a picture of them laying down on their side, that should provide you with a good view of the nub.

    If you had success using the nub theory then we’d love to know! Send us a message on Facebook, Instgram or Twitter!