The following is a wonderful blog post about how a history of sexual abuse can affect pregnancy and childbirth. Once resource that I didn't see listed is a book called "When Survivors Give Birth" by Penny Simkin. I am hoping to have a copy in our lending library soon.
If you don't feel like you can talk about your care provider about your history you may want to consider finding one who you do feel you can talk to or hire a doula that you are comfortable with to talk with about it. Your doula will also help you maintain some sense of modesty during the process if she is aware but your care provider isn't. It's also very important for your partner to be aware of the history and to know what is going to make you feel more comfortable during childbirth.