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22 / 04 / 2011 - Newer contraceptive Pills `double the danger of blood clots` compared with older versions
Women using newer brands of the Pill may be at more than double the risk of dangerous blood clots compared with those using older types, say researchers.
All brands of Pill slightly increase the risk of developing clots, which can lead to deep vein thrombosis in the leg or arm and a potentially fatal blockage in the blood supply to the lungs – a pulmonary embolism.
However, a U.S. study which included data from British general practices says there is more than double the risk depending on the type of the hormone progestogen used in the product.
Doctors writing in the British Medical Journal want women to be given ‘low risk’ Pills as a first choice. Others dispute the findings, saying an international panel of experts found a similarly low level of risk of developing blood clots from any type of Pill.
The panel says having a family history of blood clots, being overweight and smoking raise the risk, irrespective of the Pill brand.
A study from Boston University School of Medicine found a twofold increased risk in non-fatal blood clots in women taking a drospirenone-containing Pill – such as Yasmin – compared with women using a levonorgestrel-based Pill – Microgynon, for example.
If 100,000 women were on the newer Pill for a year, there would be 30 such events, compared with 12.5 on the older type.
In another analysis, using GP data from the UK, the study also found a considerably increased risk for women taking drospirenone-containing brands compared with those using levonorgestrel-containing pills – they reported 23 cases per 100,000 women, compared with 9 for those using older Pills.
The researchers said that levonorgestrel-containing Pills were ‘a safer choice’.
However, Dr Anne Szarewski, editor-in-chief of the Journal of Family Planning and Reproductive Heath Care, said a major European study found no difference in thrombosis rates between different types of Pill.
She said: ‘All Pills carry a risk but it is misleading to suggest some are less safe than others.
‘A family history of blood clots is most important in assessing a woman’s risk factors but she may be too young for this to have become apparent.
‘Other research also stresses the importance of smoking, which doubles the risk, and being overweight.’
According to the NHS National Prescribing Centre, all combined oral contraceptives increase the risk of venous thrombosis.
But an international panel of experts in 2009 found blood clots caused by the Pill were a ‘rare event’, with the highest risk in the first few months of use which falls away to similar levels seen in non-Pill users.
The risk of having a blood clot triggered by pregnancy is far higher, with about 60 cases per 100,000 pregnancies.
Source: Jenny Hope - Daily Mail