Hello,
I've been employed now for 5 months and I'm the only girl in our base. I didn't have a problem with it yet, but I don't think my company would appreciate it, if I were pregnant. We only have a few women in the company, and none of them has been pregnant. So I don't know how they would react.
Being (the only) woman has both advantages and disadvantages. They will do an extra effort for you, carry the bag,... but they will also watch you more critically (especially some of the cabin crew).
Good luck