Period drama: It's 1991's tearjerker, My Girl. It wasn't easy to find the 200 scenes ("many more menstruation scenes than I could have ever anticipated") Rosewarne eventually isolated, as the subject is often so well hidden and appears far less regularly on TV than is representative of real life. "When menstruation does appear, it is treated as a drama. It is either traumatic, embarrassing, distressing, offensive, comedic or thoroughly catastrophic" she writes in the study, published today, which is shortly being released as a book, Periods in Pop Culture. "All the big-ticket moments in life, I leant from film and TV - apart from menstruation. Actually, it is referred to, but not by name. It's often innuendo or euphemism - it's there but it's negative," Rosewarne told Life & Style. Take a scene from Superbad, when one male character realises he has blood on his jeans. "Oh my god, she perioded on my leg" is his reaction. "It's as though menstruation is like defecation or vomiting - like you can actually do it to somebody."

Superbad, another culprit, adding to the fear factor of periods in drama. Or a scene in Californication, Rosewarne recalls, when "Hank is looking after his daughter, Becca. It's the weekend she gets her first period. He takes her to a gas station and argues over buying the last box of tampons - and ends up reducing menstruation to some kind of toilet problem." Then, there's the 1976 film, Carrie, which holds the unlikely gong for most traumatising menstruation scene of all. "The fusion of a naked girl, shower stream, screaming and blood harked back to cinema’s most famous shower horror scene from Psycho. Even though the audience presumably recognized Carrie was only menstruating, the character’s terror was contagious," writes Rosewarne. The overall view is out-of-line with its place in women's lives, she says. "In line with the idea of it being something foreign, menstruation is shown in a humourous and dramatic way, rather than as normal everydayness. It's done in an extreme and outlandish way that relies on humour, negativity, exaggeration and drama."

And this means that menstruation is seen as a dirty, unhygienic function. "It goes back to biblical understandings," she says. "As if it needs to be managed through attention to cleanliness, as if it is disgusting and loathsome." Away from the screen, the problem is far from fictional. "Girls in real life are viewing menstruation as a hassle, women are happily filling prescriptions to make it go away, men are mocking it, loathing it and rarely understanding it," she writes. "On screen presentations likely have some complicity." Rosewarne hopes her research will underline "the need for good quality sex education in schools that is given to both boys and girls." Separated sex education classes have meant that boys do not learn about periods and on TV, advertisers need to be able to use frank language in an environment away from taboos. "Blood and periods are never mentioned - instead there's this blue liquid we see." "It's the problem of women feeling they are unable to articulate what's going on in their bodies," something that she says needs to be adressed, given that girls are getting their periods earlier than ever before.

Scripts may demonise periods, but half of the world's population will go through them for at least 30 years of their lives, after all. "TV is seen as being some kind of mirror on society. When it comes to menstruation, it is not."