What is the Nub Theory?
Between 11-13 weeks every baby is said to have a 'nub' between their legs also known as the genital tubercle and according to this theory the angle of the nub indicates whether it is a boy or a girl.
Boy nubs are said to be over a 30 degrees angle in correlation to the spine, please see an example below:
Girl nubs are said to be under a 30 degrees angle in correlation to the spine, please see an example below:
This theory is most accurate between 11-13 weeks. At 13 weeks the accuracy rate is 94%, at 12 weeks it is 91% and at 11 it is 48% accurate.