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.

Vaginas basically have a self-cleaning mechanism.

Your vagina's natural pH levels are constantly balancing itself, making sure that the inside of your vagina doesn't become a breeding ground for bad bacteria. The bacteria responsible for keeping the levels balanced is called lactobactilli.

"It's normal and healthy for a woman to produce a clear or white discharge from her vagina. The vagina is designed to clean itself with natural secretions," according to Dr. Vanessa MacKay, a spokeswoman for the Royal College of Obstetricians and Gynecologists.

A healthy vagina has a pH value of somewhere between 3.8 and 4.5.

"Healthy discharge doesn't have a strong smell or color, but women may feel an uncomfortable wetness," MacKay added.

So if your panties have white spots, it's a sign that your vaginal discharge is protecting you from becoming susceptible to sexually transmitted diseases, inflammation, and bacteria, such as bacterial vaginosis.

Has this ever happened to your dark panties?