Hi sunnyday! I'm not sure about the cm thing - I honestly think that it has more to do with what you've eaten and just body chemistry in general than the gender of the baby - but I know it's hard not to analyze everything! As for biorhythms, I'm interested in them too, even though it's still all in fun! If you tell me your birthdate (and your DH's if you want to check his biorhythms too), the time zone you're in, and the conception date, I'll let you know what the biorhythms say. (And if you know the conception dates for your other kids, I can check to see if it worked for them.) If you'd rather do it yourself, I posted a few days ago and described how to do it. The title of the post is "Anyone tried biorhythms lately?". Good luck!