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Nub Theory is a fact, You can't argue with science!

Photo credit - science source



This way has up-to 99.9% accuracy*

I can't stress enough that this isn't just a theory and is an actual science backed method of identifying the gender from a mid-line sagittal view. (side profile) 

Using this way is more accurate than looking between the legs before 20 weeks. 


When you are between approximately 12-13 weeks pregnant you will have your dating scan. This scan dates the pregnancy, this is vital for accuracy when using nub theory.

Nubs are visible from 9/10 weeks! but have not started to change from its "female state"

Your baby's genitals then begin to develop around the late 11th -12th week of gestation, this happens when the chemical messengers  "hormones" trigger the difference of the two sexes. For a boy testosterone kicks in and changes his nub into his scrotum and penis, for a girl, this is her developing labia/clitoris.

For best accuracy 13+weeks Is recommended! however this top accuracy can be given to boys in the 12th weeks! (I will fully explain this all in your reading if applies)

What Do I Do? 

When assessing your images, I will look at the appearance of your baby's developing genital nub, The shape, size, length, angle and bladder will be analysed to give you a predicted gender result.

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. 

But its only the Nub theory can accurately tell you the gender of your baby! with up-to 99.9% with gestation!

So, what happens in the twelfth week and the way our anatomy changes? 

The labioscrotal folds previously contained within the genital tubercle are now separating.

In male fetuses the scrotum (not testes) is descending below the penile bump, which is being pushed up and away from the rump.

In females, both labia are now forming around the clitoral protrusion. 

Of course, these changes don’t mean that by the end of week twelve, baby has a fully developed set of genitalia. Both clitoris and penis will still protrude between the legs at a similar length, meaning sexing shots, or “potty shots” are still inaccurate at this gestation.

Studies have shown that during the twelfth week of gestation there is around an 88% chance of accuracy. However, these studies were based on live sonography scans, when the nub can be viewed from many angles, and the position of the spine etc could be accurately determined. believe that from still images displaying the nub and spine clearly, between twelve weeks - four days and twelve weeks and six days, the accuracy increases to 92-98%.

This is why submitting the exact age and ALL scans, videos is you have them is really important. Nub theory is based on what baby measured on the day of your scan.

The measurement we are looking for is the gestation based on CRL (crown to rump length),

normally printed on your scan or in your maternity notes

for example; 12w 3d or 13w 2d (weeks and days)

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