The words that you use...

I know for many parents they have moments where they are tired, stressed, etc. and despite loving their child(ren), they get frustrated. I get that no one is perfect or has a perfect life, but for the love of fuzzy little puppies. NEVER EVER EVER say to your infertile friend that being a parent is the worst thing ever and you wish you could undo it. Quit saying "oh, just take one of mine". It is insensitive and it will cause your infertile friend unspeakable pain. Want to complain about parenting? CALL YOUR PARENT FRIENDS. Would you ever say to a wheelchair bound person how annoying it is to walk and stand all the time? I would hope not! Apply some common sense and don't be an ass to your infertile friends either. Now, not all infertiles are "out" like I am, so you may not know if your friend is child free by choice, or if they are crying themselves to sleep at night, err on the side of caution.