BOSTON, April 22 (UPI) -- Women taking "third generation" contraceptive pills developed in the 1980s face more health risks than those who use older varieties, U.S. researchers say.
A study found women taking birth control pills containing drospirenone are up to three times more likely to suffer a blood clot than those who use older formulations using levonorgestrel, The Daily Telegraph reported Friday.
Studies of the two types of birth control drugs by Susan Jicks of Boston University School of Medicine and colleagues found a "dramatic" difference in the level of risk, the newspaper said.
In previous studies, scientists warned women taking third-generation pills with drospirenone were at greater risk of developing blood clots in the deep veins of the legs or the pelvis.
Called venous thromboembolism, the clots can be fatal if they move inside the circulatory system and lodge in the lungs.
The study was based on data from U.S. medical claims and from the U.K. General Practice Research Database.
"These findings support more recent studies that suggest that drospirenone oral contraceptives are not as safe as levonorgestrel oral contraceptives with respect to venous thromboembolism and, in the absence of other considerations, should not be the first choice in oral contraception," the researchers said.
The study was published online in the British Medical Journal.