A newly conducted study on Wednesday presented estimates that newer kinds of contraceptive pills carry a higher risk of dangerous blood clots.

Researchers confirmed that certain versions of the birth control pill that include the synthetic hormones drospirenone (found in Yasmin), desogestrel (found in Kariva and Mircette) and other newer formulations are linked with higher risk than older birth control pills.

Researchers in the study, published in the BMJ, compared oral contraceptives containing a synthetic version of the hormone progestogen with earlier versions of the pill.

As per experts, the third-generation pill, introduced in the 1990s, and the fourth generation that got approval in the last decade, have been specifically designed to avoid side-effects of older types of the contraceptive.

Europe's drug watchdog in 2013 conducted a safety drive after France's medicines agency found that the newer pills had a small risk of serious blood clot called venous thrombo-embolism (VTE).

But the newly conducted study broadens the understanding, trawling through two large British prescription databases to take into account pill dosage, body fat, smoking and other factors which affect risk.

The study found that women using older oral contraceptives were found to have about two and a half times increased risk of VTE as compared to those women who did not use oral contraceptives.

It was told that women using a newer version of the contraceptive had around a four times increased risk of VTE compared to women who did not take the pill.

Study showed that risk for women using newer pills were around 1.5 to 1.8 times higher than for women using older pills. But when talking in absolute terms, the risk was quite low.

Researchers found that there were six extra VTE cases per year per 10,000 women using the newer levonorgestrel and norgestimate pills. These cases rose to 14 extra cases per 10,000 users of desogestrel and cyproterone.