While the current pill is popular and used by millions of women, many remain concerned about possible links with breast cancer and blood clots.
Now a pill being developed by researchers at Edinburgh University could stop periods and reverse these health risks. But it could prove controversial, as it contains the drug mifepristone, also known as RU486, which is used to induce abortions.
Professor David Baird, emeritus professor of reproductive endocrinology at Edinburgh, said the research team hoped to persuade a pharmaceutical company to develop the pill. This might not happen with mifepristone but with other agents that acted in a similar way.
Next month marks the 50th anniversary of the first clinical trials of the contraceptive pill, which led to a sexual revolution in the early 1960s.
But Prof Baird said that in recent years, contraception had fallen off the national and international priority list.
"Many people have taken it for granted that we have access to safe and effective contraception, but various issues still need to be addressed in the next 20 years," he said. "Although the pill is highly effective and safe, there is still a problem with people remembering to take it, and it doesn't suit everyone.
"There can be side-effects, such as an increased risk of breast cancer or thrombosis.
"It is theoretically possible to design a type of pill that is not only safe but also protects against these long-term risks."
The combined pill in use today combines the hormones oestrogen and progesterone to stop eggs being released from the ovaries. Some of the side- effects are thought to be linked to the actions of these hormones. The new pill works differently, by blocking progesterone, which prepares the body for pregnancy.
Prof Baird said stopping this hormone should cut the cancer risk. In addition, the pill would stop women having periods, which cause high levels of hormones to circulate in the body, and would therefore also be of benefit to woman who suffer from premenstrual syndrome.
"Women who don't take any pills have quite a high risk of developing breast cancer," Prof Baird said. "If you reduce the cyclical exposure of the ovary to the ovarian hormones oestrogen and progesterone, you should reduce the risk of breast cancer."
But it could be 20 to 30 years before scientists know whether the new pill cuts the risk, after it is used by large numbers. After nine years of studies involving about 100 women, including some in Edinburgh, Asia and Africa, Prof Baird said the pill had been shown to be successful as a contraceptive, with "very few" side-effects.
He accepted there might be concern at the use of an abortion drug in a contraceptive.
"But this pill uses a 100 times lower dose than that used to induce an abortion," he said.
Dr Anna Glasier, director of sexual and reproductive health at Edinburgh University, said the risks associated with the combined pill could be over-emphasised, to keep women informed of even minute dangers.
According to the Family Planning Association, the benefits of using the pill outweigh the risks for most women.
Dr Gillian Vanhegan, of the sexual health charity Brook, said: "Although the risk of breast cancer is only slightly increased for women who use the combined pill, this can be a deterrent."
Jeremy Hughes, the chief executive of the Breakthrough Breast Cancer charity, said: "Large, long-term studies are needed to determine the effects, if any."
Thinking again on use of pill
WHEN Jo Menzer's mother was diagnosed with breast cancer she began to look back at her own past use of the contraceptive pill in a different light.
Ms Menzer, 31, a charity administrator, was taken off the pill she was using by her doctor about five years ago amid fears that certain types of the contraceptive were linked to an increased cancer risk.
Ms Menzer, who lives in Glasgow's West End, said after her mother, Lesley Levy, was diagnosed with breast cancer last year it made her think differently about many aspects of her life.
She said she was unsure whether she would start using an oral contraceptive again.
"I would probably do some further research into it. What has happened to my mum has made me look at every area of my life and what I put into my body."