The U.S. Food and Drug Administration has released an updated safety communication regarding drospirenone-containing birth control pills, following its review of the results from an agency-funded study. According to the FDA, Bayer Pharmaceutical’s widely-used birth control pills, Yaz and Yasmin, are 75 percent more likely to cause blood clots in women than older-generation pills.

The study, which was published in the agency’s most recent drug safety report, followed approximately 800,000 women between the years 2001 and 2007. Researchers from the FDA, Kaiser Permanente, Vanderbilt University and the University of Washington ultimately found that drospirenone-containing birth control pills increased the risk of blood clots, otherwise known as venous thromboembolic events (VTE), by 75 percent over pills containing progestin levonorgestrel.

Moreover, the study’s findings back thousands of claims brought against Bayer and others, by women who experienced serious blood clots as a result of using drospirenone-containing birth control pills like Yaz, Yasmin, Beyaz, Gianvi, Loryna, Safyral, Syeda Zarah and/or Ocella. The FDA will present the new data at a December 8th meeting of the Reproductive Health Drugs Advisory Committee and the Drug Safety and Risk Management Advisory Committee.