There's now additional evidence that newer types of birth control pills, including Yaz and Yasmin, are more dangerous. Researchers found women taking the newer pills, which contain drospirenone have more than twice the risk of developing blood clots than those who take older pills, which use levonorgestrel. Another study found women taking the newer contraceptives have a 2.7 times greater risk, but overall the risk of getting a blood clot is still fairly low.