Women that take birth control pills with the newer hormone drospirenone possess a greater threat for getting potentially severe blood clots than ladies who take birth control pills that contain the older hormone levonorgestrel, two new studies show.
The women in the experiment who went on the pills containing drospirenone, such as Ocella, Yasmin, Yaz, and Zarah, had a twofold to threefold greater danger of non-fatal blood clots as compared to women who took birth ccontrol pills that contained levonorgestrel, including Jolessa, LoSeasonique, Quasense, Seasonale, and Seasonique.
But Bayer, the maker of Yaz and Yasmin, states the research was flawed.
Study researchers say the risk to individual users is modest. They estimate that around 3 women out of 10,000 who take the pill with drospirenone for a year could be expected to develop a clot, compared to about 1.2 women in 10,000 who take levonorgestrel.
“The [clot] threat during pregnancy is a lot higher than for any oral contraceptive,” said study researcher Susan S. Jick, PhD, of Boston University School of Medicine. “Nonetheless, women taking these pills or considering taking them should take note that there's very likely a greater threat associated with their use.”
At least four other studies have linked use of pills with drospirenone to an elevated risk for pulmonary embolisms and deep vein thrombosis. However all 4 studies included women with known risk variables for the conditions.
These women were omitted from the newly published studies, in which researchers reviewed medical claims data among women on birth control pills in the U.S. and the U.K.
In the U.S. study, women on pills with drospirenone were two times as likely to experience non-fatal blood clots as women on the older-generation levonorgestrel-containing pills.
In the the United Kingdom study, the use of the drospirenone pill was associated with a three time increase in risk.
The researchers demand a systematic assessment of all the studies examining blood clot threat connected with the use of oral contraceptives that contain drospirenone.
“Meanwhile,” they write, “as no obvious proof exists to show that the use of the drospirenone pill gives benefits above those of other birth control pills in preventing pregnancy, treating acne, alleviating premenstrual syndrome, or avoiding weight gain, prescribing safer levonorgestrel pills as the first choice for patients wishing to take birth control pills would seem wise.”
