Can someone explain the nub theory to me?

[kellbell827]

Hi ladies! Can someone just give me a simple explanation of the nub theory? I had an u/s at 7w3d on 1/24 and won't have another one for a few weeks but if I get the opportunity, I would love to know what I am looking for. Thanks!!

[nuthinbutpink]

http://genderdreaming.com/forum/ultrasound-gender-prediction/60-nub-guessing-between-12-14-weeks.html

[kellbell827]

Thank you!!!!