Periods aren't pornographic and they certainly shouldn't be offensive. They are a regular reality for half of the world's population and, let's be honest, without them humankind wouldn't exist. So the idea that an Instagram user could be offended by a picture of a woman whose period had leaked through her PJs onto her bed sheets is downright ridiculous.
Anyone who has either experienced a period or knows anything about them knows that there is nothing luxurious about the feeling of menstrual cramps, or discovering your purse is empty when you've run out of tampons. Without affordable sanitary products, those women who menstruate are prevented from leading a normal life, both in public and in private.
I've met women who are overdosing themselves on painkillers trying to manage their pain, who have to sit on black bin liners during their period to protect the sofa, who have been told at the age of 25 that the only solution is a hysterectomy - even one who was told by a consultant gynaecologist that it was normal to bleed for 15 days every month.