By Clare Murphy
Health reporter, BBC News
The pill: a medication or a lifestyle choice?
It is 50 years since the pill was first approved as a contraceptive, finally divorcing sex from pregnancy. But half a century on, our relationship with the tablet credited with revolutionising women's lives is not always an easy one.
On 9 May, 1960, the American authorities announced they would allow a hormonal pill previously used for gynaecological complaints to be prescribed as contraception. Over the next decade, a string of other Western countries from Australia to the UK would follow suit.
Science, changing social attitudes and even fears about overpopulation in communist states all conspired to make the pill possible.
Scientists had known for years that high doses of certain hormones stopped ovulation, but despite extensive research using German policemen's urine and thousands of sheep ovaries, it seemed almost impossible to extract the quantities needed for production on any meaningful scale.
It was not until the discovery that progesterone could be synthesised from the Mexican yam met the money and enthusiasm of two women committed to the cause of birth control, that the project took on a life of its own.
The pill also appeared just before the scandal broke over Thalidomide, the wonder-drug often prescribed for morning sickness which led to serious deformities in babies. This resulted in an overhaul of regulatory procedures.
"But it's very unfair to suggest those involved weren't bothered about safety - when you look at the records kept there was definite caution. The problem is we judge them according to post-Thalidomide standards," says Dr Lara Marks, author of Sexual Chemistry: a history of the contraceptive pill.
"It's true you would have a much harder time getting this off the ground today. The regulatory climate is completely different - but women themselves are much more critical and questioning about what they are being offered.
"We probably wouldn't put up with the serious side-effects of the first pill as so many women did back then, but then we don't understand what it was like to live in a world before legal abortion."
Now the pill is one of the most studied medications in history, the subject of many ongoing epidemiological investigations. More than 200 million women worldwide have used it since it was first approved.
Its popularity has ebbed and flowed over the years amid various health scares - from thrombosis to cancer, and it has demanded an understanding of relative risk like no other drug. Risk, when it comes to offering healthy people a long-term drug, is perceived quite differently from weighing up the pros and cons for someone who is sick.
The last major health scare occurred in the mid-1990s, when it was found that the "third generation" of pills put women at a higher risk of venous thromboembolism, which can be fatal in some cases.
While the research was solid, there was criticism of the way it was presented - giving women little understanding of their overall risk - not least in comparison with the risks of being pregnant.
It was later concluded that the scare probably did save a handful of women from clots, but the thousands of extra unwanted pregnancies put many more at risk. The abortion rate in the UK rose by 8% in the following year, equivalent to 13,000 terminations.
The research suggests a possible, marginal increase in breast and cervical cancers among those taking the pill, but lifelong protection against ovarian cancers. Indeed, a study published earlier this year of 46,000 women - some followed for almost 40 years - found those on the pill less likely to die of any cause than those not.
For healthy, non-smokers there appears to be no reason why the pill cannot be taken until the age of 50, but doctors agree those with a history of blood clots, breast cancer, stroke or heart disease should steer clear - as should anyone who is very overweight, has high blood pressure or continues to smoke beyond the age of 35.
No free lunch
But even if the serious health problems appear to be now in context, the pill is still regularly under fire. Just this week German researchers suggested it may reduce libido.
The exact link is unclear but, in an editorial accompanying the study, Dr Irwin Goldstein of the Journal of Sexual Medicine suggested there may be consequences of meddling with one's hormones.
"The irony is that these women are provided a medication that enables freedom from reproductive worries, but these same women are not provided information that there are significant adverse sexual effects that may ensue," he said.
What the next 50 years will bring is unclear. The pill is still much preferred over long-acting reversible contraceptives such as implants or intrauterine devices, despite the fact these methods - unlike the pill - need very little thought or action.
There is regular talk of a male contraceptive, but above and beyond the debate as to whether women would trust men with their birth control, practically it is simply much harder to shut down constant sperm production than stop an egg being released every month.
In the UK, making the pill available without prescription, free from the medical authorities, remains controversial - for both moral and medical reasons.
"But this is what should be happening, going forward. All the research shows that when women feel they are the ones in charge of their contraception, making decisions about it, they are more likely to use it," says Lynn Hearton of the Family Planning Association.
"It won't be for everyone, and some women will want to see their doctor. We'd need to ensure that all the information was out there. But 50 years on it really is time to stop being so paternalistic. The pill is a medicine, but it's also a lifestyle choice, and it's one we should trust women to make."