I am so sorry that you are going through that crap. And that is what they are pulling....CRAP. I am a nurse in a ICU too (though not an OB nurse) and I have seen nurses on our unit be passive agressive like that towards our pregnant nurses. I can't figure out what is wrong with people. I don't blame you for putting in for a transfer. If you explain to your manager that you like working there ( if you do) but the stress is too much for you at this time and need to seek another option, I wouldn't anticipate a problem. Plus it shows professionalism and honesty on your part so your not burning a bridge that you may need some day, whether it is for a reference or wanting to go back some day.

Anyway, goodluck and keep you chin up.

Leslie