Quoting TeamJumpingBean:" I'm currently 20 weeks along and go next week to find out the sex of the baby. I have had names picked ... [snip!] ... was four months old. So I don't want someone stealing the names that I have picked out again...Has this happend to anyone else?"
I'm pretty certain it has and I have heard it happened alot. That's why I don't share combos that are at the *very* top of my list.
But as a general rule, if you are very territorial over your child's name, it is best to not tell until after the baby is born.