Scientists are working on a new generation of chemical contraceptives which could hugely reduce side-effects, including the risk of breast cancer and blood clots, 50 years after the first trial of the pill.
Laboratory studies suggest that, aside from stopping women getting pregnant, the new pill could reduce breast cancers, thrombosis, and heart disease associated with the existing pill. It also stops women having periods altogether - suggesting it could offer relief for the hundreds of thousands suffering from PMT.
But it will be controversial because the new group of compounds include a drug known as mifepristone, which is licensed in the UK for use in chemical abortions.
It is the first offer of an alternative to the progesterone and oestrogen combinations that are taken by 3.4 million women in the UK, but it is expected to take five years to reach the market.
Most recent advances have sought to end the need for women to remember to take the pill. Patches, injections and implants have been introduced in the UK, and scientists are also confident they have developed a pill for men. A European partnership between two companies is looking at marketing the product, primarily to men who are considering a vasectomy but wanting something reversible. The new female pill would also be an alternative for women worried about health risks.
David Baird, the Edinburgh University professor leading the government-funded trial of the drugs on 97 women, said: "On theoretical grounds, because it contains no oestrogen, it should not have the same risk that the combined pill has."
Adding mifepristone to cancer cells grown in the laboratory limited their growth, and tests on mice showed a reduction in progesterone-sensitive breast cancers. More studies were needed to examine benefits and side-effects, he said.
The link between the current pill and breast cancer is disputed. Doctors also point towards the protective effect it is known to have against cancers in the ovaries, womb and perhaps bowel.
But Professor Baird said that there was resistance to developing mifepristone as a contraceptive pill, because of lobbying from anti-abortion groups which oppose its use in terminations.
"The political background to mifepristone means it's unlikely that it will reach market - but there are others of the same compound that will."
The drug is being investigated for use as a contraceptive at doses of between 2 and 10mg. As an abortion pill it is prescribed at doses of 600mg.
Phyllis Bowman, chief executive of Right to Life, said there were questions about the safety of mifepristone. She cited studies which suggested up to eight women had died in the US after taking it to induce abortions.
The new pill also stops periods, which experts at a briefing yesterday suggested would be welcomed by some women. Anna Glasier, director of sexual and reproductive health research at the London School of Hygiene and Tropical Medicine, said: "The idea that not having a period is unnatural is not true. Years ago women would be pregnant, or breastfeeding and died much earlier; we had far fewer periods."
Toni Bellfield, head of information at the Family Planning Association, said it welcomed new contraceptives, but feared that a pill offering protection against breast cancers would over-emphasise the risks of other oral contraceptives.
Backstory
In April 1956, the first large scale field trials of the contraceptive pill took place in Puerto Rico. The country was chosen by American scientists because it was not anti-birth control. A high dose was used and while it proved 100% effective at preventing pregnancy, 17% of women had severe side effects including vomiting and fainting. The trial drew criticism for experimenting on women in the developing world. Nevertheless, within four years the pill was being prescribed in America and in 1961 it came to the UK. The daily dose of the pill first prescribed to women equals about seven of today's daily doses and scientists have been refining it ever since. According to the Family Planning Association, about 3.4 million in the UK take the pill, 2 million taking the combined pill. In 2004, 25% of all women of childbearing age used the pill. The Austrian scientist Carl Djerassi whose work is credited for leading to the development of the pill is now a playwright.
