US Pharm
. 2015;40(6):21.

Nottingham, UK—A new study has found that oral contraceptives containing newer types of progestogen (cyproterone, drospirenone, desogestrel, gestodene) are more likely to cause blood clots than older versions with levonorgestrel, norethisterone, and norgestimate. Researchers at the University of Nottingham analyzed two large patient databases of women aged 15 to 49 years in the United Kingdom who were taking birth control pills. Compared to women who did not use oral contraceptives, those who took the newer pills were four times more likely to develop blood clots, and 2.5 times more likely with the older pills. The investigators stressed that the overall odds of a clot remain very low for any one woman taking oral contraceptives, and still remain much lower than the 10-fold increased risk that occurs during pregnancy.

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