Im not sure about the refusal part, but they start an IV, for one, to keep you hydrated, after you are in labor, you cannot drink anything by mouth in case you need anesthesia and second, it gives them access to your veins if you need any kind of medication fast, so they don't have to poke you every time. Ask your doc about it too. We have our tour of the hospital tomorrow night, I could sure ask them and let you know!
You HAVE to get the I.V., there is no way around it, most of the time, if you have not gotten your group B strep test results back yet, they give you an antibiotic through the IV, and this is to keep you hydrated also. I can promise you that once you are in labor, the iv will not even be on your mind. I am not trying to say that you are going to be in pain, I am just saying that with all the excitement and emotions going on, you aren't going to even think about it!