Re: what do they do when 1 twin dies inutero?
I want to preface this whole post by saying I THINK this is what happens:
If the babies do not share a placenta, then generally the pregnancy just continues until the surviving twin is ready to be delivered. At delivery (which I think will likely be a c-section), the doctors will probably ask if she wants to see the twin that passed away. If they do share a placenta, there can be serious complications, including the surviving twin's heart trying to pump blood for both babies.
I think each situation is different, and without more specifics, it's really hard to say. One thing I would mention, though, is to be very sensitive to the fact that the mother still IS pregnant with twins, she will give birth to twins, the surviving baby will always be a twin, and the mom's loss is just as real as if she had lost a baby in a singleton pregnancy.
Mid-pregnancy we faced a crisis that left us with a high chance of losing one or both babies. We were lucky and so far we have made it through without complications. But I spent a lot of time on boards chatting with people who had lost one of their twins during the pregnancy, and over and over they expressed how hard it was when people politely ignored the death of one of the babies. When you're pregnant with two, you don't love each one half as much as if you were pregnant with one. Everyone mentioned that the worst thing that had been said to them was something like "at least you still have one baby."
Obviously you are a very caring and concerned person, otherwise you wouldn't have posted with your message in the first place. I just thought I would share with you what little bit I know about the emotional side of this. Also, from what I've read, a lot of parents feel better seeing the deceased baby after delivery, rather than just having the doctors take it away, like a tumor that had been removed. Some even take pictures with mom holding both babies together, as a reminder that these babies are twins, even though one passed away. I know it may seem a bit morbid, but it's still her baby, and still the surviving baby's twin. Some families find it easier to grieve if they have concrete evidence that the twin pregnancy was real.
If it turns out the baby has died, you may want to read a bit about the emotional side of it, and offer your support to the mother when she is ready. There is an organization called CLIMB (Center for Loss in Multiple Birth) that might be a good resource for you or her. I don't know anything about it other than the name, but I think you might find some good information there.
I hope everything turns out ok, and that your family gets the support it needs in dealing with this tragedy.
Identical boys, Max and Jack born 3/19/05!