Matchstick-sized contraceptive implant that lasts for three years

The Food and Drug Administration in the U.S. has given approval for a new contraceptive which will protect women from pregnancy for as long as three years.

The matchstick-sized implant is made of a soft medical polymer and is inserted just beneath the skin on the inner side of a woman's upper arm by a doctor in his office.

The device releases a low, steady dose of synthetic progesterone hormone each day to block the release of an egg from the ovaries.

The state of the art implantable technology is called Implanon and is produced by Akzo Nobel NV and proven to be 99% effective in a study involving 923 women at preventing pregnancy.

Once the rod was removed fertility was quickly restored sometimes within 30 days, says Dr. Scott Monroe, FDA's acting director of reproductive and urologic products.

In the trial 11% of women had Implanon removed because of irregular menstrual bleeding and some women experienced no menstrual period at all while using the device.

An earlier device, the controversial Norplant produced by Wyeth, was withdrawn from the market in 2000 after tests found thousands of implants may have been faulty.

Implanon is not expected to have as many problems because it involves implanting only one rod rather than Norplant's six, and is not inserted as deeply under the skin.

Many of the complaints regarding Norplant involved insertion or removal of the rods.

Implanon has been trialled in more than 30 countries with more than 2.5 million women since 1998 according to Akzo and the company has promised to allow only doctors with training in how to insert and remove Implanon to prescribe it.

That training will start later this year and is expected to be more widely available in 2007.

Women's groups have welcomed the device as another option for family planning but stressed women need information up front about the device, especially removal.

Women and doctors are advised to rub the skin to make sure the implant is there after the insertion procedure.

As with other hormonal contraceptives, Implanon may increase the risk of blood clots.

Other hormone-based methods currently available in the United States include birth control pills, a skin patch, a ring inserted into the vagina and a shot given every three months.

Implanon does not protect against HIV infection and other sexually transmitted diseases.

As with any progestin-only contraceptive irregular bleeding can occur; other changes may include more or less frequent bleeding, bleeding for a longer or shorter duration, or absence of bleeding and may vary throughout the duration of use.

Other side-effects include headache, acne, dysmenorrhea and emotional instability, which are all common to hormonal contraception.

Some implant site complications were experienced by 3.6 percent of study participants and they included, swelling, redness, hematoma and pain.

Removal complications were also low and included: implant not palpable, broken or damaged implant, difficult localization, slight migration and formation of fibrosis.

The use of hormonal contraceptives is associated with increased risks of several serious side effects, including thromboembolic diseases.

Cigarette smoking increases the risk of serious cardiovascular side effects and women who use hormonal contraceptives are strongly advised not to smoke.