When you're in a field enviroment that doesn't have supplied restrooms (Outhouses) there's a sudden increase in urinary tract infections, and it's not the men getting them.
I doubt that's a huge issue.
There will never be many women in front-line combat roles, even if it does become legal. But the fact is that women
do already serve in frontline combat all the time, because there aren't really any front lines in Iraq or Afghanistan. And they have done extremely well, as well as male soldiers.
There are certainly problems with an integrated service. Rape, pregnancy, and psychological issues are all concerns. But it seems as if the benefits outweigh the costs.