Contraception that suits to a T

Annabel Ferriman looks at Mirena, a system that seems to combine the best features of the Pill and the coil while avoiding some of their unpleasant side-effects

Although the 10th-century Persian physician Al-Razi claimed that a woman would not get pregnant if she sneezed, blew her nose and jumped violently backwards seven times after having sex, most women these days look for slightly more reliable methods.

From today, they will have another option. A new method, described by one expert as "the most significant advance in reversible contraception since the invention of the Pill", is being launched at a medical symposium in London, linked via satellite to Edinburgh, Leeds, Birmingham and Cardiff.

The new system, a cross between the intrauterine device (IUD) and the mini-Pill, consists of a plastic T-shaped frame, with a store of progestogen round the vertical stem, which is slowly released into the womb over three years. It provides a much lower dose of contraceptive hormone than the Pill, as well as reducing the side-effects commonly associated with the coil. It works by keeping the endometrium (lining of the womb) thin and thickening the cervical mucus through the local hormonal effect.

John Guillebaud, professor of family planning and reproductive health and medical director of the Margaret Pyke Centre in London, believes it combines the advantages of the two methods, while avoiding most of their drawbacks. "Like the Pill, it has enormous efficacy and convenience. Trials show that the risk of becoming pregnant with it is 0.15 per 100 women years. In other words, if 1,000 women used it for a year, between one and two women would get pregnant."

The progestogen hormone, levonorgestrel, that it delivers also appears to provide some protection against infection. It alters the cervical mucus, which stops some bacteria entering the womb.

"In addition, because the progestogen is delivered directly to the uterus, and acts locally on the endometrium, the dose can be smaller than in the Pill. The system delivers weekly the equivalent of only one or two mini-Pills, instead of seven," he says.

The device, called Mirena and manufactured by the Scandinavian firm Pharmacia- Leiras, is already licensed in five Scandinavian countries. It is fitted like a coil. As with the coil, users do not need to remember to take a pill every day. It is a contraceptive in which the "default state" is one of contraception, unlike pills and condoms, where the default state is the reverse, conception.

It does not have the coil's disadvantages, however, of increasing the risk of infection and making periods heavier and, sometimes, more painful. The return to fertility after removal is rapid.

"It rewrites the textbooks about IUDs," says Professor Guillebaud. "One disadvantage of the coil is that it increases the risk of infection, which can affect a woman's fertility. But with this method, the risk of infection is not increased, and seems to be reduced.

"Unlike the coil, it makes periods lighter rather than heavier, reducing blood loss by 70 per cent, and for a fifth of those using it, periods disappear altogether.

"I am sure that it will become the contraceptive method of choice for many women, particularly older ones who have heavy periods.'

Although Professor Guillebaud makes the new method sound like the greatest breakthrough in contraception terms since the invention of the wheel, he points out that there are some disadvantages. First, unlike the condom, it does not give protection against HIV and Aids. Second, it is slightly harder to fit than the usual copper coil, particularly in women who have never had a baby. It might require a local anaesthetic, and is probably not a first-choice method for women without children.

Finally, for the first few months after it is fitted, as the lining of the womb gradually comes away, slight bleeding occurs. Some women find that they have to wear a small pad almost continuously.

"We have found that if you warn women about this, they bite the bullet and put up with it until the benefits arrive," says Professor Guillebaud. "Similarly, if you tell them that they might lose their periods entirely, and that this is not harmful in any way, they find that an advantage rather than a disadvantage."

Cathie Fraser, a 43-year-old professional woman from west London, tried the system as part of the Margaret Pyke research programme. "I was willing to try a new method, because I had been on the Pill on and off for 20 years," she says. "I tried a normal coil, but it gave me cramps. The mini- Pill did not suit my lifestyle, because you have to take it at exactly the same time every day, and, because I do shift work, that was not easy.

"I have been on the new method for just over two years and have had no discernible side-effects. My periods have more or less disappeared, which does not worry me in the least."

Miss Fraser, who has a long-term partner, did not find the fiting difficult, despite the fact that she has never had children. "It was no worse than a smear test. I bled for a while at the beginning for a month or two, but it was nothing dramatic. I like it because it is so permanent, but reversible."

The new method will not appeal to everyone. It still means that small doses of steroids are circulating in the user's bloodstream, even though the levels are much lower than with the Pill. But it does provide another option from which to choose.

There are other methods, of course. As Woody Allen once said: "I want to tell you a terrific story about oral contraception. I asked this girl to sleep with me and she said 'no'."