A contraceptive pill that promises an end to the misery of menstruation for millions of women has been proved safe and effective.
The pill, called Lybrel, is taken continuously 365 days a year and halted periods in more than half the 2000 women who took it.
It is the first pill designed to eliminate the fertility cycle.
Conventional oral contraceptives are taken for 21 days a month with a break of seven days during which the woman has her period.
But some gynaecologists say there is no reason women should continue to suffer the pain, discomfort and emotional disturbance associated with menstruation.
They say it is easily eliminated and no different from treating the menopause with hormone replacement therapy or impotence with Viagra.
Lybrel is not yet licensed, but its maker, the American company Wyeth, has applied to regulators in the US and Britain, and it is expected to go on sale there next year.
David Archer, professor of obstetrics and gynaecology at the Eastern Virginia Medical School, said there was a rising tide of awareness and discussion on eliminating periods.
"But it will always be predicated on what women want and are prepared to tolerate.
"What we have done is taken an oral contraceptive and tweaked it to give women another choice."
When the first contraceptive pill was introduced in the 1960s it could have been designed to eliminate the fertility cycle, Professor Archer said.
But no simple pregnancy tests were available, and scientists believed women would want the reassurance of a monthly period as proof that they were not pregnant.
In 1977, the first trial of "extended use" oral contraceptives, in which women took the pill for months at a time, was carried out.
"The results showed the consumers liked it but the doctors didn't," Professor Archer said.
In 2000, two fertility experts from the Population Council of Mexico, Sarah Thomas and Charlotte Ellertson, delivered an impassioned plea in the UK medical journal The Lancet for modern drugs to end menstruation.
"Any woman can tell you that menstruating is a pain, literally and metaphorically," they wrote.
"At a minimum it is a nuisance that requires planning, expensive sanitary supplies and paracetamol to avoid messy discomfort for about one week each month.
"In many cases, however, it has a far greater impact. Hormonal fluctuations accompanying the menstrual cycle have medical consequences that are largely ignored. Women are expected to function as normal and minimal attention is paid to physical and mental discomfort."
The monthly period had been "mythologised and socialised" into being the natural state for women. Yet it was an anomaly in medicine.
"There can be no other condition that affects so many people on such a regular basis which is not prioritised by health professionals or policy makers," they said.
Professor Archer said the findings of his study showed 58 per cent of women were completely free of periods after using the pill for a year. But some women had irregular bleeding, which was unexplained.
"This product is not for everyone. But for women who want to suppress their periods it is a good choice," he said.
A spokeswoman for Britain's Family Planning Association said the group welcomed extra choice in contraception for women.
"Some women do not like the inconvenience of periods but other use them to check they are not pregnant."