Hi Jennifer - long time no see! I still have this board in my "favorites" and stop by from time to time.
What a difficult situation you are in.
If they are planning to terminate her - they'd best do it before she tells them the news - if they terminate her after a pregnancy is announced - there could be problems. Oh - wait - I just realized as I typed this that you work for lawyers - so I don't need to talk to you about labour laws - lol.
Does she have a probation period? Would they be doing an overall review of her performance shortly?
That's a tough one and I don't envy you at all. I suppose all you can do is present them with the facts regarding her work performance and see if they give you an indication as to weather they'll be taking action (ie terminating her or having a talk with her and looking for specific things she must improve by a certain date).
Now you'll have to post - but I'm curious how this will end.
You are really caught in the middle.
Take care, Jo