The most talked about theory across the internet, "The Nub Theory"

The worlds number one early gender prediction.

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The nub theory is scientifically proven to be the most highly accurate form of early gender prediction. When examined by one of our experts, it can predict the sex of your  baby just by simply analysing your baby's nub from their 12 week dating scan.


The genital tubercle bump will start to develop from around 8 weeks in gestation, this wont be seen via ultrasound until the 11th to 13th week. All babies have  a nub between their legs called the genital tubercle,  the angle of the nub will help indicate whether your baby is a boy or a girl. If the nub is over 30 degrees from the spine, its a boy - but if its under 30 degrees, its a girl. 


All nubs will image as a fork. This fork is split into two parts. The bottom half also known as the urogenital folds will develop into the labia minora, and the top half will develop into the clitoris and will continue to retract into its final resting place in the weeks to come. 

For male fetuses the genital tuber will develop into the glans of the penis,

the urogenital fold becomes the shaft and the labioscrotal fold matures into the scrotum.


There is a lot of confusion around the bladder position and how this helps determine your baby's gender. The bladder is not any different in males or females.

The bladder should only be used as an anchor to measure the axis, which helps determine if this is above or below 30 degrees.


The developing female nub varies at different gestations, the nub here is parallel to her spine, it also sits below 30 degrees and you will also find her nub hangs directly off her rump.


The developing boy nub you see below is above a 30 degree angle, he is also showing full scrotum and penis in development. You will notice the nub is shaped with a short white line with a very visible white bump on the top.


Nub Theory accuracy ranges......From 11 weeks in gestation, the accuracy is around 70%. The reason for this is that all baby's will present with a nub that is parallel to the spine, this is because the nub is still in development and making rapid changes....

From 12-12.5 weeks there is a huge range in accuracy, between 80-98%, this is based on a whole lot of factors, such as the visibility of the nub, the angle of the nub, the position of the fetus, the thickness of the abdominal wall, image clarity and BMI. Drinking a pint of water before you have your ultrasound can help to get the baby moving and get a clearer picture for a prediction.

By having one of our experts analyse your scan images it will help you to understand the difference between the actual nub and what may be mistaken for cord, leg and sometimes foot. 

When you make a purchase with us, we will check the visibility of your baby's nub, the angle in which it points too, the shape and overall look, we will also check for stacking or shadowing and the bladder position in which we use as an anchor. All factors mentioned above are taken into account when predicting your baby's gender. These factors are also backed by science and with that proves  to be the most accurate way of determining gender.

Unfortunately not all images will show a nub shot if this is the case, we will email and let you know and a full refund will be offered or we will offer the option of predicting through The Ramzi Theory  


Below you will see 4  examples, these examples will show you why this theory is not accurate at 11 weeks.

Two of these nubs presented girly, but were later confirmed by ultrasound to be boys. The other two nubs look slightly boyish in appearance but were later confirmed to be girls.

The rapid changes between 10-12 weeks can lead to a lot of incorrect predictions.




nub theory

We often get asked, if a nub is showing as a fork it has to be a girl, is this right?

This information is actually incorrect. As you can see from our examples, we illustrate

how a male nub is angled above 30 degrees, you can also see the tip of his nub

points upwards indicating a baby boy. We also illustrate a female nub shot which is

angled below 30 degrees, the nub points downwards and sits flush to her spine indicating a baby girl.The length and shape of your baby's nub may sometimes indicate gender, but not always.

For example, some say that a “forked nub” is indicative of a girl fetus, however we do not

adopt this, as its clear that both sexes can be seen with a forked nub in the early stages of development.  The reason you see a fork shaped nub in both female and male fetuses, is because this fork serves an important purpose. For females, this fork will become the labia and clitoris, for males, the top half of the fork will develop into the penis, and bottom fork into the scrotum.We also know a forked nub is a sign of an undeveloped nub or a late riser (in males)


The "stacked" nub as it's most commonly known consist of the developing penis and scrotal line. Both can be seen imaging in bright white at the base of baby's body. The penis is seen as a round shape, while scrotal line is located right underneath and longer in length  this images as a short line (but not always)

Female nubs can sometimes image in funny ways too, this makes them appear as "stacked". This happens when the top part of the fork on baby's nub, also known as baby's clitoris has been captured at an off angle. These angles can often lead to much confusion and wrongful prediction of baby's sex in the nub theory community. 



The information provided to you is backed by many years of knowledge on the the theory. We are not medical professionals nor do we provide medical advice.

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