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The progestogen content of combined oral contraceptives and venous thromboembolic risk

BMJ 2011; 343 doi: (Published 25 October 2011) Cite this as: BMJ 2011;343:d6592
  1. Philip C Hannaford, Grampian Health Board chair of primary care
  1. 1Academic Primary Care, University of Aberdeen, Aberdeen AB25 2ZD, UK
  1. p.hannaford{at}

New evidence confirms that differences exist between preparations with different progestogens

In the linked study (doi:10.1136/bmj.d6423), Lidegaard and colleagues assess the effect of different types of combined oral contraceptive, according to progestogen type and oestrogen dose, on the risk of venous thromboembolism.1

Over the past four decades, more than 25 epidemiological studies have examined the risk of venous thromboembolism in current users of combined oral contraceptives.2 All but two studies found a significantly higher risk among current users compared with non-users. The risk is probably greater during the first few months of use, before falling to a level that remains above that of non-users until the use of these contraceptives is stopped, when the excess risk rapidly disappears. Early studies examining the effects of the hormonal constituents tended to focus on the oestrogen content of particular products, although one report suggested that the progestogen content may also be important.3 Focus on the progestogen content sharpened in the mid-1990s, when several publications reported a higher risk of venous thromboembolism in users of combined oral contraceptives containing the more recently introduced progestogens, desogestrel or gestodene, compared with those using products with the older progestogen levonorgestrel. These results, replicated in subsequent studies, …

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