A Dutch research team has published a new study concluding that Yaz has a greater risk of causing blood clots than other birth control pills.
The Dutch cohort study looked at over one million women from 2001-2008. Researchers confirmed nearly 3000 venous thrombotic events (VTEs), or blood clots, during that time frame. This was a follow up to their 2009 publication that was widely criticized by Bayer’s scientists. This study confirmed other studies which have shown:
• Birth control pills carry an increased risk of venous thrombosis (VTE).
• The risk was higher with some pills including Yaz than with other, safer “second generation” pills.
• Results on the risk from Yaz have been conflicting; but 4/6 studies have found an increased risk.
What this study adds to the previously published studies:
• Women using Yaz are at similar risk of VTE to those using oral contraceptives with the progestogens: desogestrel, gestodene, or cyproterone.
• Women using Yaz are at a higher risk than those using oral contraceptives with the progestogen, levonorgestrel.
• The risk of VTE was not reduced by using Yaz with 20 μg estrogen instead of Yasmin with 30 μg estrogen.
• To prevent one event of VTE in one year about 2000 women should shift from using oral contraceptives with desogestrel, gestodene, or drospirenone to those with levonorgestrel.