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"Third generation" oral contraceptives are linked to
a more than doubled risk of potentially fatal blood clots known
as venous thromboembolisms.
The research from Boston University School of Medicine in Massachusetts
indicates that oral contraceptives containing desogestrel or gestodene
increased the risk of blood clots by a
factor of 2.3 compared to older birth control pills containing
levonorgestrel.
The findings support earlier research about the potential danger
of the "third-generation" pills that caused a scare in
1995 and resulted in a warning to doctors and pharmacists about
the potential dangers. Since the warning, the number of women taking
the "third generation" pill, have dropped by about 80%.
The researchers estimated that if women had not switched after
the warning there would have been about 26%
more cases of blood clots.
In an emailed response to the study, Anthony Griffiths points out
that the "third-generation" pills might me of use to women
in certain situations, such as women suffering from the androgenic
effects of polycystic ovarian disease syndrome (PCOS) and women
at an increased risk of heart disease.
Women with PCOS would benefit from the greater estrogenic effects
of the "third generation" pills.
Women at increased risk of heart disease would be better off avoiding
the levonorgestrel pills which can lower the levels of cardio-protective
HDL cholesterol.
British
Medical Journal November 11, 2000;321:1190-1195
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