You may have noticed that your dark shades of underwear start to turn white inside after some time.
If you've never freaked out over seeing that, then you're alone on this one. Most people make themselves feel better by attributing this to their laundry detergent or the bad quality of their underwear, but it's actually your vagina causing those "bleach" stains.
Your vagina has some superhuman-like capabilities that you're not even aware of.
Although they're delicate, they're incredibly strong. You have to be very careful on how you wash them and what products you use on them, but they're able to stretch enough to allow a baby to pass through. Also, women can get kicked there without feeling much pain, which is a bonus.
Rest assured. There's really no need for you to worry about the crotch area of your underwear changing color, it's actually a good sign.