Worry not, the bleached patch in your underwear is normal

Among its many other superhuman qualities, your vagina has the power to change the colour of your knickers.

Specifically, it’s able to "bleach" them.

If you've ever noticed a bleached patch in your underwear then it could be the work of your vagina's natural pH levels.

As worrying as this may sound, it's actually a good sign - rather than an indication that something's wrong, or gone awry in the laundry.

PH levels determine how acidic or alkaline something is. When there's a level lower than seven that indicates acidic properties.

A healthy vagina has a pH value of somewhere between 3.8 and 4.5 - so more on the acidic end of the scale.

While this may sound unpleasant and alarming, it's simply our body doing its work.

Naturally occurring bacteria called lactobactilli keep the vagina's pH at a normal level, The Sun reports.

The acidity of your vaginal discharge is what protects you from nasties such as thrush and bacterial vaginosis.

If the acidity level is not where it should be, then this can also leave us susceptible to sexually transmitted diseases.

So your discharge, with its acid levels, has the ability stain or alter the colour of your underwear - something you may notice with dark coloured underwear.

Dr Vanessa MacKay, a spokeswoman for the Royal College of Obstetricians and Gynaecologists, said: "The vagina is designed to clean itself with natural secretions.

"The vagina contains good bacteria, which are there to protect it.

"If these bacteria are disturbed it can lead to infection, such as bacterial vaginosis or thrush, and inflammation.

"It's normal and healthy for a woman to produce a clear or white discharge from her vagina.

"This mucus is produced naturally from the neck of the womb, known as the cervix.

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

So there you go - just another amazing thing the vagina does.