Newer Pill Version May
Increase Blood Clot Risk
By Merritt McKinney

NEW YORK (Reuters Health) - Women taking the newest version of the Pill may want to reconsider their choice and start taking older versions of oral contraceptives, according to Dutch researchers. A review of studies has confirmed a previously noted link between ``third-generation'' birth control pills and an increased risk of potentially fatal blood clotting called venous thrombosis.

The risk of blood clots remains small, but women should be told of the link so they can weigh the risks of the newer drugs against their benefits, one of the study's authors told Reuters Health.

``Women who are already using a third-generation oral contraceptive should be informed about the higher risk of venous thrombosis,'' said Dr. Jeanet M. Kemmeren of the University Medical Center Utrecht in the Netherlands. ``Based on this information they may decide to change to a second-generation oral contraceptive.''

But depending on their risk for blood clots, some women may also weigh their own experience with other side effects, which may be less frequent with the third-generation Pill, according to Kemmeren.

``We believe that it is a task for the pharmaceutical industry to develop oral contraceptives that do not cause a higher risk of venous thrombosis,'' Kemmeren said.

Both second- and third-generation birth control pills contain a form of estrogen called ethinylestradiol coupled with another hormone called a progestin. The difference between the two types of pills is the type of progestin they contain. The newer contraceptives contain either desogestrel or gestodene, and the older ones contain levonorgestrel or norgestrel.

According to Kemmeren, third-generation birth control pills were developed to reduce the side effects of earlier versions of the Pill, which included weight gain, acne and harmful changes in cholesterol levels. The newer drugs have been shown to have a less harmful effect on cholesterol, Kemmeren said, but it is unproven whether this improvement decreases the risk of heart attack or stroke.

Beginning in the fall of 1995, several reports in the UK linked third-generation versions of the Pill to an increased risk of blood clots. But some experts were skeptical of the research. They suspected that the researchers had not accounted for factors that might have been responsible for the increased risk.

To resolve the controversy, Kemmeren and her colleagues reviewed a dozen studies performed up to the fall of 1995 that evaluated the risk of blood clots among women taking oral contraceptives.

The results of the review confirm the link between third-generation birth control pills and an increased risk of blood clots, the researchers report in the July 21st issue of the British Medical Journal. Women taking the newer versions of the Pill were 1.7 times more likely to have a blood clot than women taking the older drugs.

This risk translates to two additional cases of blood clots per 10,000 women per year, according to Kemmeren.

Although the risk of blood clots is small and is highest in women taking the drugs for the first time, women should weigh the risks and benefits before choosing a contraceptive, Kemmeren and her colleagues conclude.

The Dutch researcher told Reuters Health that women at high risk of blood clots, such as those with a family history of the condition, should be advised to take a second-generation version of the Pill. But women who do not have any risk factors and who are concerned about side effects of the older drugs, such as weight gain, acne and facial hair growth, may want to consider third-generation oral contraceptives, she said.

Despite the controversy over the safety of oral contraceptives, Dr. J. O. Drife, of the General Infirmary in Leeds, UK, points out in an accompanying editorial that the risks of oral contraceptives pale in comparison to the risks of pregnancy for many women.

``While debating whether risks are 1 or 10 in a million, we should remember that in most of the world the risk of death associated with pregnancy is at least a hundred times higher than this,'' Drife writes. ``Many thousands of lives could be saved each year if contraception were more widely available in the developing world.''

Drife has received past funding from Schering UK, which makes oral contraceptives, but the research did not involve contraception.

SOURCE: British Medical Journal 2001;323:119-120, 131-134.

Reference Source 89

For more information on how to prevent other diseases, use
PreventDisease.com's "Quick Prevention Resources".