What is the nub theory?

[CuriousGeorgie7]

I have seen many posts about this, can someone explain how it works and any guesses on this scan photo?

Bump

It’s a 50/50 guess!
in theory it’s the angle of the genitalia of the foetus, but in reality it’s nothing more than guess work….now watch the pile on of ‘no you’re wrong, I correctly identified two hundred and fifty million nubs….”
All I can tell you is it’s definitely a baby in the making, and you’ll love it regardless of sex.
congratulations.

@mazedasamarchhare aww thank you x