Strange question - during my period the strectchmark on my stomach goes blue - why?

[TheDevilWearsPrimark]

It's odd, very odd, the rest of the time it's just white/skin coloured.

Lol I have no idea, but I have a mole at the top of my cleavage thats gets darker about a week before I'm due, once my periods finished it get's lighter again.

Perhaps it's something to do with extra bloodflow?