RPM is safe for women on birth control.
Honestly this is not very good advice. I am not scolding anyone or discrediting anyone but unless you are a doctor it is hard to tell someone something like this without detailed studies or knowledge in the area.
In fact naringin, a compound sometimes used to increase absorption, could definitely affect women on birth control by giving them a larger than normal plasma concentration of the drug in question, depending on brand (some contain extra compounds). Not saying there is a possibility of getting pregnant, but it is definitely a factor.
Not only that but procyanidin dimers were shown in studies to reduce estrogen levels. Again I am not saying this will have anything to do with taking birth control in the doses that you would be taking, but it is definitely something to consider.
Whatever you decide just be sure not to take the rpm near the time you take your birth control.
EDIT: I am not trying to turn people away from a product, because I have heard great things about it I am merely here to inform.