Does anyone know the number of male doctors versus female doctors?

I’m writing a research paper and I’d like to mention the number (percentage) of male vs. female doctors in the U.S., both as a whole and also within the field of obstetrics. I’ve tried doing google searches but can’t seem to find anything relevant. So if anyone knows offhand or is able to find something, that would be very helpful! I’d prefer something reliable, like a .gov, .org, or a scholarly writing, not something off wikipedia or anything, and obviously I’d need to cite it as well, so please include your source if you can find anything. Thanks!!