Greater risk of blood clots with vaginal rings and skin patchesRisk double that of taking the pill
Women who use vaginal rings, implants and skin patches are at greater risk of developing serious blood clots than those who take the contraceptive pill, a large study has found.
Several studies have assessed the risk of blood clots in women taking the contraceptive pill, but few have investigated the risk associated with taking non-oral hormonal contraceptives such as vaginal rings, implants and skin patches.
In a study published online in the British Medical Journal, researchers from the University of Copenhagen analysed data from more than 1.6 million women aged between 15 and 49 from 2001 to 2010. None of the women had a history of blood cots.
During the study period some 3,434 women were diagnosed with their first blood clot.
For women not using any type of contraception, there was a two in 10,000 risk of developing a blood clot each year.
But for those taking a combined contraceptive pill, the risk was three times higher, at 6.2 in 10,000.
However, the risk of developing a blood clot was higher with types of non-oral hormonal contraception.
Compared with women of the same age not using hormonal contraception, women who used a skin patch had an eight times increased risk of a blood clot, while women who used a vaginal ring had a 6.5 times increased risk.
The risk associated with using skin patches was also double that of women taking the contraceptive pill.
Progestogen-only subcutaneous implants carried a slightly increased risk, while use of a progestogen-only intrauterine device did not confer any risk, and may even have a protective effect, the researchers said.
Unlike the combined contraceptive pill, no reduction in risk was seen with long-term use of a patch or a vaginal ring.
Based on the study findings, the researchers calculated that 1,250 women using a skin patch or 2,000 using a vaginal ring would need to switch to the combined contraceptive pill to prevent one woman developing a blood clot each year.
Professor Ojvind Lidegaard, who led the study, said: "The most important thing is that women are informed about the risk.
"If women still prefer to have a ring or a patch, for example because they are not able to remember to take the pill daily, then they can continue. That is their own choice.
"For me, the important thing is that they are informed about the risk."
Dr Ellie Birtley, lead clinician at the British Pregnancy Advisory Service, said: "Women using these methods should not panic.
"The risks of venous thrombosis raised by these forms of contraception are still significantly lower than the risks to women who are pregnant.
"There are now a large number of contraceptive methods available, and women should consult with their doctor or nurse to find the method that is most suited to them and their lifestyle, and therefore most likely to protect them against unwanted pregnancy."
This article was published on Fri 11 May 2012
Image © catherina holder - Fotolia.com
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