Two studies published in the British Medical Journal found that women taking pills containing a newer type of progestin were at higher risk for blood clots.
According to the reports, women who took pills containing drospirenone, which includes the brands Yasmin, Yaz and Ocella, more than doubled their risk of non- fatal blood clots. This compares to women taking older varieties of oral contraceptives.
Experts also stress the overall risk of blood clots with any birth control pill is still considered quite low.
In a statement, Bayer, the maker of Yasmin, says the methodology used showed significant flaws. The company also cites 10 years of safety study results since the pill was introduced.