GTM-WG8XH27 google-site-verification: google95a6d318fda64b63.html Nub Theory | Nub Theory Explained | Gender Prediction

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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 A genital tubercle or phallic tubercle is a body of tissue present in the development of the reproductive system. It forms in the ventral, caudal region of mammalian embryos of both sexes, and eventually develops into a primordial phallus.

All babies have a ‘nub’ between their legs, this is called the genital tubercle, until about 7-8 weeks of pregnancy, both sexes will have a preliminary set of genitalia that will eventually differentiate to become either the male or female sex organs. This means, that both male and female genitalia start from the same foundation.  The genital tubercle comprises of three areas, the genital tuber, Urogenital fold and the labioscrotal fold.
​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.
​For female fetuses the urogenital folds develop into the Labia minora and the genital tuber continues development into the clitoris.


These Images show a 12 week old baby's genital tubercle and the stages from 6-14 weeks on how the genital tubercle develops.


We get asked often, if a nub is showing as a fork it must be a girl? This information is  actually incorrect. If the nub is angled greater than a 30 degree angle in relation to the spine and flicked up, it is likely you are having a baby boy. If it is pointing straight out, down, and under a 30 degrees angle, it is likely you are having a baby girl.

As you can see from our examples, we illustrate how a male fetus’ genital tubercle is angled above 30 degrees you can also see the tip of his nub point upwards indicating a baby boy. From the right we illustrate a female fetus' genital tubercle 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 the genital tubercle may sometimes indicate gender, but not always. For example, some say that a “forked” shape at the tip 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 in the nub of 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 the developing penis and scotal line. Both can be seen imaging in bright white at the base of babys body. The penis is seen as a round shape, while scrotal line is located right underneath and longer in length imaging as a line.-- 

Female nubs can sometimes image in funny ways that make 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. 

(Predicting your babies gender from as early as 12 weeks)


In some of the study groups, when the angle of the genital tubercle was an intermediate angle of 10 to 30 degrees the fetal gender was not determined.Out of a total of 1619 pregnancies; gender was assigned and confirmed in 1424. The table below shows the results in so far for accuracy of fetal gender prediction at a routine first trimester scan. 

The fetal gender was assigned as male if the angle of the genital tubercle to a horizontal line through the lumbosacral skin surface (lower portion of the spine) was greater than 30 degrees and female when the genital tubercle was parallel or convergent (less than 10 degrees) to the horizontal line.


Prenatal gender assignment by ultrasound has a high accuracy rate at 12 to 14 weeks. At 11 weeks there was an error rate of 50% and only 14/100 assigned correct male gender. In the male fetuses after 12 weeks, there was a significant increase in the angle of the genital tubercle from the horizontal. The accuracy of sex determination increased with gestation.

credit - Babycenter