A new study has found that women who take the newer forms of birth control pills could be at a higher risk of suffering blood clot.

It was found that women taking some of the newer formulations had about four times the risk of a blood clot, called venous thromboembolism or VTE, as a woman not taking any birth control pill.

The researchers, in their  report published in the BMJ, the online journal of the British Medical Association, however pointed out that the overall risk is still very low with just 14 cases out of every 10,000 women.

Explaining this,  Dr. Barbara Levy, vice president for health policy for the American College of Obstetricians and Gynecologists (ACOG) said it was far lower than the risk of being pregnant.

Furthermore, pregnant women have 10 times the risk of a blood clot because estrogen, contained in most birth control pills, makes the blood more likely to clot.

Newer birth control pill formulations use a different type of a second hormone, called progesterone or progestin, it's however unclear why they carry a higher risk of blood clots than older ones do.

Data from 10,000 women across Britain was analysed by Yana Vinogradova of Britain’s University of Nottingham and colleagues and about half of them had been diagnosed with a blood clot.