But Micks says, physiologically this isn’t a real period at all. And it isn’t necessary. “There’s absolutely no medical need to have a period when you’re on contraception,” she says.

So why have women been having all these “fake” periods for decades? “It’s actually a historical thing,” she says.

One of the doctors who helped invent the pill was Catholic. He thought the pope might accept the pill if it looked like women were having periods.

But the Catholic church never came around to the pill. And when doctors actually asked women if they wanted to have these fake periods, many said they didn’t.