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

(71 ratings)
baby scan, ultrasound, boy or girl, pregnant, pregnancy,

Can you tell if your baby is a boy or girl from just 12 weeks? 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.

However, the nub theory claims to be a lot more accurate - and says 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 a little 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.

    Continued below...


    If you had success using the nub theory then we'd love to know! Leave us a comment below or send us a message on our Facebook page.

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    • 3
    (71 ratings)

    Your comments

    Claire31

    Any ideas? Boy or girl?!

    Claire31

    Any ideas? Boy or girl?

    Christina Jones-Jenkins

    Not letting me c thr pic

    day13

    Any guessers on my 11 week nub shot?

    charlie

    can anyone guess if its a girl or boy, this scan is at 13 weeks

    charlie

    any idea of what my baby is this is at 13 weeks

    Kursty Marie Cunniff

    Got 2 boys already

    Kursty Marie Cunniff

    13weeks 5days

    Kursty Marie Cunniff

    Any ideas 13week 5 days thanks Kirsty

    ash

    Girl:)

    smiler

    Any guesses if the gender is boy or girl, please??

    Chelsea

    Leave a message...

    Erin

    Im not sure wot to think, i dont know what my scan pics looks more like. Its hard to tell Lets wait and see ha.

    Lynsey

    Hi I know what I think it is, what do u think girl or boy, seems clear xx

    Kat

    Any ideas boy or girl?

    mai

    please guess, boy or girl?

    kat

    Please help - This is 12 weeks scan of my baby. Please guess the gender.

    jammyminxy

    Hospital have said its a girl :)

    jammyminxy

    At 20 week scan the hospital says it is a girl :)

    jammyminxy

    Defo a girl I would say - it looks like my scan which is a girl!

    jammyminxy

    Girl

    Claire

    Would you say boy or girl please? im 12 weeks 3 days :)

    beth x

    boy or girl guys????

    natalie

    i seen this in my last ultrasound at 11 weeks and 5 days. im confused?? not sure if its a penis or a nub?

    jade

    I'd say a girl. I have two girls.

    jade

    Hi any ideas on whether my scan is showing a boy or a girl ? Thanks

    Tietiex

    is the nub were im pointing to?

    leigh

    Hiya people any ideas on boy or girl. Many thanks

    Guest

    It's not allowing me to put a picture up anyone know why many thanks.

    leigh

    That looks like a girl to me it's the same as my first baby.xx

    jammyminxy

    Cheers thanks! Any more thoughts on todays scan at 15 weeks??

    paige

    could anyone tell me what they think im having please

    Lgeyen

    Any guesses?

    Sarah Glover

    Any ideas please?

    Christina Jones-Jenkins

    Looks girly

    Christina Jones-Jenkins

    Looks boyish

    Christina Jones-Jenkins

    First pic looks boy...second pic looks like mine girly. Im gona guess boy!

    Jammyminxy

    Can anyone tell if they think we are having a boy or girl, please? Thanks

    Sophie

    What sex do you think? I had just turned 12 weeks when I had this scan????..

    Guest

    I'm now 17 weeks. At the time of my scan I had just turned 12 weeks...what sex do you think?

    Kayleigh Blake

    What do you all think my baby is? I find out in the morning so if anyone gets back to me I'll let you know :-)

    Guest

    Boy or girl

    tracywrigley@hotmail.com

    Hi guys any idea boy or girl

    Shannon

    Any one plz help

    Shannon

    Anyone plz !! Really want to no

    Shannon

    Can any one help boy or girl plz

    Shannon

    I need to no mine help

    emerald

    any guesses boy or girl? thanks

    emerald

    Any guesses please boy or girl?

    emerald

    any guesses??? Girl or boy?

    Kel x

    Any ideas of the gender based on the nub theory please xx

    danni10

    boy

    danni10

    looks like a girl

    danni10

    boy/girl ??

    danni10

    can you see from the pic weather this little one is a boy or a girl

    Guest

    any ideas on boy or girl

    Delilah

    Girl

    Delilah

    This is the twelve wk scan of our fourth baby, after 3 boys we've been for gender scan today at 16 wksand this little one is a GIRL

    Ivelisse Divine Reyes

    Please help!! I can't tell.. Any guesses if it's a boy or a girl?

    dooleyx

    Boy or Girl???

    elisa douglas

    Hi was wondering if anyone has any ideas what we could be having? as i don't have a clue lol thank you :)

    elisa douglas

    Hi was wondering if anyone has any ideas what we could be having? thank you :)

    миша кохт

    babyy gender determination before birth and conception. Baby gender determination by photo of parents only. To do this I have an account and a group on Facebook. The group is called Baby gender by parents photo

    Kayla Bentley Sharkey

    someone give me an idea on what the gender is my brother in law said girl coz the nub theory but I have no idea I have a boy so girl would be amazing thank you x

    Sarah

    Any guesses? X

    Kerry Skea

    wonder if you ladies can help me. do you reckon I'm having a boy or girl? xx

    Melissa

    Boy or girl ? Scan is 12 weeks 6 days.

    EMMA

    any idea boy or girl

    EMMA

    any idea boy or girl... this is 12 weeks scan

    Danielle

    Girl

    Danielle

    Boy

    Claire Storrie

    Boy or girl ?

    Marium Mujtaba Lakho

    m 12 weeks 2 days can you help me if its a girl or a boy?

    Marium Mujtaba Lakho

    girl or boy?

    Marium Mujtaba Lakho

    can anyone help me if its a girl or a boy

    laura

    Boy or girl 12 week 1 day scan

    dev

    guess .. boy or girl

    dev

    hi, Guess Boy Or Girl.

    sammi

    Boy or girl?

    Rachel

    Boy or Girl 12+6

    yasmin8989

    boy or girl ?

    yasmin8989

    10+3 week boy or girl ?

    Megan

    12weeks 2 days... any ideas? :) x

    kimbeydarling

    Boy?

    kimbeydarling

    Boy or girl please xx

    Virginia

    I think the nub is just beside left hand marker technician left....

    Virginia

    PLEASE help me guess the gender..... My daughter has three ____s and this is her 4th and final try for a ___ ??????

    Virginia

    Girl

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