Sometimes when there is a bath in the room, the hospital policy is not to allow a waterbirth but just to allow them for pain relief. It depends on the depth of the water. Also in a bath you can be restricted for movement. Speak to the hospital and if this is in fact their policy you may be able to take an inflatable birth pool into hospital with you (depending again on their policies). They may also have a larger birthing pool somewhere which is very awesome for labouring.