Pill Doesn't Greatly Increase Risk of Blood Clots
Aug. 18, 2000 -- Five years ago, doctors and patients became alarmed by reports that some newer combination birth control pills might double or even triple the risk of blood clots in the veins. In the U.S., the FDA made no move to ban or issue warnings about the pills, choosing instead to wait for more information. But in the U.K., the 'pill scare' caused many women to stop taking the pill or change their birth control method.
Now a study in the current issue of British Medical Journal refutes the contention of some of those reports that blood clots are increased by taking the newer forms of birth control pills compared to older forms of the pill. The study tracked the rate of blood clots and found that it stayed virtually the same when looking at the incidence in women in taking the pill in the years immediately before the pill scare and the years immediately after.
"If [the newer pills] had twice the risk of [blood clots in the veins] compared with older formulations, a reduction in their use would be expected to reduce [their] incidence," report Professor R.D.T. Farmer and colleagues from the University of Surrey in England. "We found no such change. No evidence of a difference was seen in any of the age groups."
An estimated 70 million women take some form of birth control pill daily. The pill is said to be the most thoroughly researched of all available medications and the most effective birth control method available. The combination pill contains two hormones, estrogen and progestogen, that work together to prevent pregnancy.
Since the early 1960s, there have been reports of a link between use of the pill and risk of blood clots in the veins. The risk decreased with the introduction of a low-dose pill containing less estrogen, but three reports issued in 1995 suggested that rates were on the rise.
In the latest study, use of the pill decreased from 54% of women surveyed before the pill scare of 1995 to 14% three years later. Farmer and colleagues found that the group of women most likely to stop taking the pill after the scare were those under age 30.