Is it permissible for a pregnant woman to go to a Muslim female doctor for reassurance about her pregnancy, and what might follow from that in terms of revealing awrah (parts of the body that must be covered), and is that considered a matter of necessity?

It is permissible for a pregnant woman to expose her 'awrah (private parts) to a female doctor when there is a need for treatment or for something that benefits her. It is permissible for a male doctor to look at the 'awrah al-mughallazah (the most private parts) for treatment when a female doctor is unavailable, because there is a need for it, not a necessity, and because it is less severe for one of the same gender to look at the other.