I don't think they were necessarily in the heat of the battle. In one the links I posted, they were captured when their island fell (Guam and Phillipines). There is at least one case of a woman being absconded from her camp/hospital, but she must have strayed from where she was supposed to be and I think she was Aussie. I did find a reference to female nurses serving on hospital ships, which would explain their presence close to the action without high fatalities. Even the Japanese stayed away from firing on hospital ships...I think. Anyway, here's the link....
United States Navy Nurse Corps - Wikipedia, the free encyclopedia