Sorry to break it to you, but it’s not just Mercury that goes into retrograde, so does your period.

But we’re not talking about astronomical phenomena here – we’re talking about the direction your period flows in.

By now you’ll be aware that we basically know nothing about our reproductive organs (thanks sex education) and it turns out that the same applies to our periods.

In a new video from Dr Karan Rajan (TikTok’s favourite doctor), he explains that our periods can actually flow... backwards.

Drawing the process on a whiteboard, he demonstrates how period blood can actually flow up the fallopian tubes and exit through the gap between the ovaries and the tubes, where it then falls into the abdominal cavity. This blood is then reabsorbed by the body.

Before this news fills you with terror – retrograde menstruation (as this process is known) is super common, with 90% of us who have periods experiencing it.

However, it can be painful if there is a lot of blood lining the cavity as blood is an irritant, as Dr Rajan points out.

If you have a condition where your cervical opening is narrower than average, you’re also more likely to experience retrograde menstruation.

He also stresses that if you have any excessive pain and excessive bleeding it’s super important that you go and speak to your doctor.

You can watch the eye-opening video for yourself below: