Has anyone heard of this and if you have has it been correct for you? I'm 13 weeks pregnant with baby #4. I have 3 boys and am really crossing fingers for a daughter. I had an ultrasound last night but I don't think they got a good shot of the "nub" but I have been sitting here analyzing and obsessing over this since last night! lol! Eh only 4-5 weeks left but it feels like an eternity!