Sorry to read of the loss of your son.
Your worry is understandable. Balance it though with the fact that she is under medical care and that they aim to do something to help her and the baby in order to prevent further complications. The mortality rates in childbirth are very low. For your daughter's sake and for yours, try to keep as positive an outlook as you can. The more relaxed she is, the better it will be. Hang in there. Sometimes we have to leave our real worries in higher hands.