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Renewed concern about pill safety

Posted on 20 August 2009 by admin

Deep-venous-thrombosis-causesA Dutch study on the safety of birth control pills shed more light on the dangers of hormonal contraceptives.

Scientists have long known that oral contraceptives, which contain the female hormones estrogen and progestogen, increase the likelihood of deep vein thrombosis of the leg and pulmonary embolism, but new studies in Denmark and the Netherlands determined that some pills are safer than others. Neither study received funding from any companies that make oral contraceptives.

Pills containing a second-generation progestogen — levonorgestrel or norgestrel — and a low dose of estrogen are safest, they concluded.

The overall risk of venous thromboembolism is low, perhaps three for 10,000 woman-years for women in general, said Dr. Ojvind Lidegaard, a professor of obstetrics and gynecology at the Rigshospitalet in Copenhagen, and lead author of one of two reports in the Aug. 14 online issue of BMJ. But older contraceptive pills double or triple that risk, and the newest generation of oral contraceptives increase the risk fourfold or fivefold, he said.

A first message from the studies is that “the risk when you are taking an oral contraceptive depends on both the estrogen dose and the progestogen dose, and the lower the dose, the less risk,” Lidegaard said.

Both studies found that the risk decreases with the length of time a woman takes a combination pill, and that progestogen-only pills and the use of hormone-releasing intrauterine devices are not associated with an increased risk.

The Dutch study, which compared 1,524 women under the age of 50 who had deep venous thromboembolisms with 1,760 women with no such history, found a fivefold increased risk in oral contraceptive users. The risk of an event was highest in the first three months of use and lowest with pills containing levonorgestrel.

Pills with equal doses of estrogen that contained the progestogen desogestrel had double the risk of the pills using levonorgestrel, the researchers found.

The Danish study of all women aged 15 to 49 from 1995 to 2005 found roughly the same association.

Women taking oral contraceptives had a fivefold increased risk of blood clots compared with nonusers, and the risk differed by the type of progestin. “The newer types of oral contraceptives containing drospirenone or cyproterone acetate are associated with an increased risk compared with oral contraceptives containing levonorgestrel,” Van Hylckama Vlieg says. Specifically, the researchers found that:

* Levonorgestrel boosted the risk of blood clots by nearly fourfold compared to nonusers.
* Gestodene boosted risk by 5.6 times.
* Drospirenone boosted risk 6.3 times.
* Cyproterone boosted risk 6.8 times.
* Desogestrel boosted risk 7.3 times.

The risk of blood clots was also associated with the level of estrogen in the pills, with higher estrogen dose linked with higher risk.

1 Comments For This Post

  1. Rod Quentin Says:

    My experience in trying to get media publicity in the UK of the book by Dr Niklaus WAldis MD ‘The Truth About the Pill’ indicates the Media do not encourage printing any negative comment about the pill no matter how true the comment is. My conclusion right or wrong is it could be they think they may antagonise readers and lose business. For this reason, I am having to think about ending trying to get publicity for the Dr Waldis book as it could have a negative effcct on sales of my other non pill books.

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