THURSDAY, April 21 (HealthDay News) -- Newer forms of birth control pills may carry a higher risk of serious blood clots than earlier oral contraceptives.
Women taking the "fourth generation" pills containing drospirenone, a new type of progestogen hormone, had double to triple the risk of blood clots compared to women taking levonorgestrel-containing pills, according to two studies published online April 22 in BMJ.
"This is confirming what a lot of physicians had suspected for some time. The new pills do have a higher clot risk. But it's still much lower than the risk associated with pregnancy, so it doesn't preclude us using it," said Dr. Rachel Bonnema, assistant professor of internal medicine at the University of Nebraska Medical Center in Omaha.
Added Dr. Steven R. Goldstein, professor of obstetrics and gynecology at NYU Langone Medical Center in New York City: "Even if the findings turn out to be real, we're talking about an increase from a very small risk to a very small risk."
These new pills -- marketed as Yaz or Yasmin in North America -- are popular, although the risk of blood clots, also known as venous thromboembolism, has been noted before.
One of the two new studies involved U.S. women aged 15 to 44 who took a contraceptive pill containing either drospirenone or levonorgestrel after January 2002.
In that study, the researchers, led by Dr. Susan Jick of Boston University School of Medicine, compared 186 women who had had a blood clot with 681 who had not.
Those taking the newer pill had a 2.3 times greater risk for a blood clot. The absolute risk, however, was still small -- 30.8 per 100,000 among those taking drospirenone, compared to 12.5 per 100,000 in women taking levonorgestrel.
The other study looked at similarly aged women in the United Kingdom and found a three-fold elevated risk for blood clots among women taki
All rights reserved