The nub theory is the theory used to decide whether you are having a boy or a girl. Its the ‘angle of the dangle’. The genital tubercle develops into either a penis or clitoris and this is possible to view from around 12 weeks by analysing the ‘nub’ in relation to the spine and other factors such as nub shape.
The accuracy of the nub theory increases the longer the gestation, therefore the older the gestation date the higher the accuracy.
Gender determination accuracy by weeks. *
12 Weeks 88%
13 Weeks 94%
14 Weeks 98%
15 Weeks 99.6%
Please Note: Before submitting your scan for the Nub theory. Please ensure the image is in profile view and your scan is dated between weeks 12-15. any scans dated before week 11 will not be as high in accuracy due to the further development that takes place from week 12.