Forty years ago this week, women first started taking the Pill. Virginia Ironside, The Independent's agony aunt and part of that first generation, asks if it was the start of all our problems

Most inventions just push out boundaries that already exist. Penicillin was a staggering discovery, but it only resulted in being able to cure people even better than before. The invention of the telephone meant we could communicate more easily than before, forays into space meant we could travel further than before.

Most inventions just push out boundaries that already exist. Penicillin was a staggering discovery, but it only resulted in being able to cure people even better than before. The invention of the telephone meant we could communicate more easily than before, forays into space meant we could travel further than before.

But nothing, not even computers or the internet, has come anywhere near having the huge effect on our social lives and how we perceive ourselves as the Pill. This Friday it is 40 years since the first Pill, Enovid-10, actually became available. The first time some woman in Illinois actually pressed it out of its little vacuum bubble and popped it into her mouth, Pandora's box was opened.

True, the Pill was an invention waiting to happen. Two world wars had meant women were working more, labour-saving gadgets were being invented to take the time out of housework, women properly got the vote in 1928, and the diaphragm became a viable contraceptive when an Oxford scientist devised a spermicide to go with it in 1932. But this new thing, this Pill, this meant that women could suddenly be available for risk-free sex every single second of every single day. Finally, they had control over their lives. Great!

Or was it? In some ways yes, in some ways no. No pain, no gain. As far as the gain went, the advantages of the Pill are pretty clear. Most of us would probably say that it was responsible for a sexual revolution that enabled women to become, bar the odd nine months here or there, equal to men.

Obviously it's a fantasy to imagine that pre-Pill every woman was keeping her legs crossed till Mr Right came along; any gutsy old lady will pooh-pooh the idea that it was members of the Sixties generation who invented sex. Certainly my own mother had squillions of affairs, and as far as I can gather, everyone in her circle was "at it like mixed hounds" as one of her contemporaries delicately put it. Of course hers may have been a slightly bohemian and arty set, but sex, and lots of it, was being had long before the Sixties. But affairs didn't seem to break up marriages quite so much as they do nowadays; sex wasn't something that was much discussed. Too much of it, for women at least, was thought to be rather naughty and even shameful.

What the Pill did was to break open this whole dam of secrecy that had been in place for hundreds of years. Overnight, young women were going round boasting how many men they'd had sex with; they were ashamed to be virgins, not proud. We were suddenly able to talk about it, even brag about it, to write about it explicitly.

I used to write a serial for Rave magazine, and, according to an outraged letter in a magazine called New Society, the unmarried, teenage bed-scene I wrote was a first. Admittedly about five episodes were devoted to the getting of the contraception, and only one to the actual act itself, which probably was described by two sentences: "...and then we fell into bed. Afterwards..." but there it was, another Pill milestone.

We wore the shortest of short skirts, fishnet tights and long, high-heeled leather boots, and most people were right when they described us as looking like tarts. The Pill enabled us to behave like tarts as well. Which was all very well, but it wasn't terribly nice being a tart, as I remember. It was a bit depressing. Suddenly the Pill started to peel off its woman-friendly mask, and reveal itself as a male mole.

Because although the idea of the Pill was to free women from sexual constraint, from the burden of pregnancy, to enable them to experience sex just like men, there was a sting in its tail. There's a strong argument that the Pill benefited men far more than women. No longer did they need to take any responsibility at all for pregnancy. They could have a field day. They could throw their anxieties, their flattery, their bunches of flowers to the wind. They could, simply, just get right in there. Unfortunately, this instant gratification, like plastic money ("Take the waiting out of wanting" - remember that ad?) meant that sex was no longer quite such fun, for women at least.

I always remember a particularly horrible man saying to me, in the Sixties: "Want to come to bed?" When I refused, he said: "Oh come on, it'll only take five minutes." Tragically confused, at 16, I meekly concurred - as, I imagine, a whole lot of teenage girls are doing at this present time. So it was only to be expected that out of these rather bleak experiences grew an obsession with great sex, and unattainably high goals of sexual satisfaction. No longer was it good enough just to enjoy sex, vaguely; no, you had to have simultaneous orgasms as well. If you weren't sexually firing on every single cylinder, you were weird and your relationship was doomed. Sex that was merely adequate became something ghastly to "work at", to see sex therapists about. The Pill took away the anxiety of pregnancy on the one hand, and delivered a whole dollop of new anxiety on the other.

The other burden of the Pill, for us women, is that even though, unlike men, we're not fertile all the time, we still have to take the Pill every day. And this means that women are suddenly available for sex at the drop of a hat. In the past, unless you carried your diaphragm in your handbag, you had to be prepared. You had to make a decision to have sex, not just have it. At the very least you'd wait until you felt sexy. But now sex is so available that it's no longer special. In the new Brook Advisory Service's much-publicised booklet for 14-year-olds and over, "Say Yes, Say No, Say Maybe", there's a grisly section called The Good Grope Guide in which the readers are told: "Nice girls feel sexy and nice girls make love. That's a fact of life." They're also told that: "Sex can happen any time - at friends', watching videos on Saturday morning, while taking a walk in the park."

But the worst effect the Pill has had is not on sex, but on society. Because young girls are encouraged to see sex in the same way as boys, they are becoming increasingly defeminised. Girl power, a direct legacy of the Pill, breeds laddishness. There's no good or bad about this - it's just one of the side-effects of the Pill, like bloating. Sex is becoming as meaningless to young girls as it is to boys. And boys, whose behaviour always used to be modified by the presence of girls ("Never use bad language in front of a lady") no longer have any restraints on their behaviour.

Everyone at the moment is in a state of flux, never a comfortable state to be in, and no one can possibly predict how it's all going to turn out in the end.

There's only one clue on the horizon. And that is that the number of teenage girls taking the Pill has fallen by 50 per cent in the last decade. Why? Although they don't mind stuffing themselves with fags, alcohol and Es, they are perhaps more sensible than the first generation of Pill-users. They just don't like taking mysterious chemicals into their bodies on a daily basis. It give them the creeps. More couples are choosing condoms as their method of contraception, interestingly putting the onus back on boys to take more sexual responsibility. And although I'm assured that teenage girls aren't using it as a form of contraception, it's interesting to see that the Brook Advisory Service reports that in its clinics the morning-after pill was used by 18,000 women in 1990/91, and nearly 100,000 in 1997/98.

It's true that the Pill seems to have landed us in something of a sexual mess, and leaves in its wake a whole set of questions about gender roles. New men don't know where they stand. Some suddenly find their rampant masculinity simply doesn't seem to have a place in today's society, particularly when faced with women who left their feminine wiles in the Sixties and turned into ersatz men, whether in their careers or as drunken louts. But we all crave roles. They may not always be particularly nice, but they give us a feeling of identity. We know where we are.

The Pill gave us sexual freedom and equality with one hand. With the other, however, it took away our security. Our next task is to find in what form that security will reappear. As, inevitably, it will.