Last year the contraceptive pill celebrated its 35th birthday amid hysterical headlines about its life- threatening side-effects. Yet these third-generation pills are the safest ever, giving just a fifth of the hormone dose contained in the pills prescribed in the early Sixties. Although the bad press caused some alarms, the pill remains the world's most widely used contraceptive. Every day more than 70 million women reach for a 21-pill blister-pack of some form or other to guard against pregnancy.

The earliest attempts at contraception were hampered by the need to compensate for high mortality rates. According to John Guillebaud, author of The Pill, physicians in the late 19th century believed that people who indulged in "sexual fraudulency" risked dreadful side-effects, including cancer, mania and mental decay.

Elsewhere in the world, however, every effort was made to lower the chances of conceiving, while increasing man's freedom to fornicate. Pity the poor women from the ancient Egyptian tribe that encouraged them to fill their vaginas with a paste derived from crocodile dung. This and other equally messy alternatives - like the ancient Chinese practice of swallowing live tadpoles in early spring - would make any oral contraceptive seem worth trying. The herbal infusions advocated by Greek apothecaries, were probably more palatable, and recent research has shown that some of the plants actually contained oestrogen and so may have worked.

Although the tadpoles and herbs could be regarded as the first oral contraceptives, the pill as we know it today was not conceived until the 1920s when the female hormones oestrogen and progesterone were isolated and their chemical formulas identified. When rabbits, famously enthusiastic breeders, had their ovaries put on hold after oestrogen treatment, the way forward was clear. But oestrogen, at this stage still extracted from animals, was incredibly expensive. After a decade, however, synthetic versions of both female hormones were developed. Schering, the German pharmaceutical company, created a synthetic oestrogen in 1938; within a year, Russell Marker, an American organic chemist, extracted progesterone from wild Mexican yams. But it was another 18 years before the first combined oral contraceptive pill was ready for human trials; these took place in Puerto Rico in 1956.

In 1961 Schering launched Anovlar in Europe. This first, commercially available oral contraceptive revolutionised family planning, but not, contrary to popular belief, the sex-life of the single woman. It wasn't until 1964, when the first Brook Advisory Centre opened, that single women could enjoy sex without the fear of conception.

The 1970s saw many advances in hormone technology, with scientists producing ever-lower doses of the synthetic forms of oestrogen and progesterone. In 1972, the first pill containing progesterone, the "mini-pill" Microlut, was launched, a year later, the world's first low-dose pill, Microgynon, followed - and became an instant hit - it is still the biggest-selling pill in the world.

There are now around 30 contraceptive pills on the market and, media scares permitting, many more will follow. Like many drugs, the pill does have side-effects, the best-known and most alarming being the risk of thrombosis. But what few people realise is that pregnancy carries a greater risk of thrombosis (though it is still minimal). Most importantly, if taken correctly, the pill will ensure that pregnancy is a risk women won't take unwittingly