MONDAY, Sept. 26 (HealthDay News) -- U.S. health officials issued a cautionary note Monday about an increased risk of blood clots in women taking newer forms of birth control pills, such as Yaz or Yasmin.
Although stopping short of a definitive statement, the U.S. Food and Drug Administration (FDA) did say it "remains concerned" about a potentially higher risk of blood clots in women taking the "fourth generation" pills containing drospirenone, a new type of synthetic progestin.
These new pills -- marketed as Yaz or Yasmin, among other brand names, in North America -- are popular, although the risk of blood clots, also known as venous thromboembolism (VTE), has been noted before.
VTEs are clots that typically originate in the legs and can travel to the lungs. They are best known as so-called "economy class syndrome" because of cases occurring during long-haul flights, although experts warn that they can happen at any time. Symptoms include leg pain, chest pain or sudden shortness of breath.
Preliminary results of an FDA-funded study show a 50 percent increased risk of VTEs in women taking drospirenone-containing pills versus other hormonal contraceptives.
The risk to any one woman remains small: overall, the risk of a VTE is about six women per 10,000 users for the older contraceptives versus 10 per 10,000 using the newer versions, the FDA said.
The agency also reviewed six other studies on the subject, the results of which were conflicting. Two studies found no difference in risk, while another two found a 1.5-fold to 2-fold increased risk.
And two more studies, appearing earlier this year in the BMJ, found double to triple the risk.
The FDA issued a similar safety communication at the end of May, after the two BMJ studies came out.
Experts advise that women who have been on Yaz, Yasmin or similar drugs should not dis
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