Why the pill gives you a monthly bleed: a short history

The monthly bleed you get on the combined pill is not biologically necessary. It is there because of a decision made in the 1950s, and the reason is not what most people expect.

A design choice, not a medical need

When the pill was developed, one of its inventors, the gynaecologist John Rock, was a devout Catholic. He built in a pattern of three weeks of pills and a one-week break that produces a bleed, hoping it would persuade the Vatican to accept the pill as a natural extension of the menstrual cycle, much like the rhythm method, which the Pope had approved in 1951. The monthly bleed was, in effect, a way of making a new technology look familiar and acceptable.

It did not even work

The Vatican rejected artificial contraception regardless. But by then the seven-day break had become the standard way the pill was taken, and it has largely stayed that way ever since, helped along by an assumption that women would want the monthly reassurance that they were not pregnant.

What this means for you

It is worth sitting with that for a moment. The way millions of women have taken the pill for sixty years was shaped, in good part, by men trying to please an institution that did not even want women to have it. The monthly bleed was never for your benefit.

The reassuring part is that the choice is now entirely yours. The Faculty of Sexual and Reproductive Healthcare is clear that there is no health benefit to the hormone-free week. The bleed it produces is not a real period; it is a withdrawal bleed caused by stopping the hormones. So if you would rather not have it, you do not have to. Skipping it is a genuine, safe choice, and we explain how in a separate piece.

That is the quiet truth of the seven-day break: a 1950s compromise, not a rule of nature.