Thousands of women continue to be denied the most appropriate contraceptive, because their doctors do not prescribe the safest Pill, or offer alternative forms of birth control, such as, patches or injections.

Two studies assessing the association between risk of blood clots with medication say, women do not routinely use the safest brand of contraceptive pills.

While, all contraceptive pills carry a risk of venous thrombosis or venal blood clots, some carry a higher risk than others, with researchers in one study finding risk of clots varied, dependent on the type of progesterone and oestrogen dose.

According to them, the safest option was the hormone combination found in popular as second-generation pills like Ovranette, Microgynon 30 and Trinordial, which have a low dose of oestrogen combined with levonorgestrel, a type of progesterone.

The authors of the study say, women taking third-generation pills, such as, Marvalon, Mercilon, Femodin, including Jasmine, the new pill on the market, are most at risk from venous thrombosis, which includes deep-vein thrombosis in the arms or legs, and pulmonary embolism.

Progesterone-only pills, with lower progesterone levels than combined pills, and hormone-releasing intrauterine devices (IUDs) are not associated with any increased risk of blood clots.

The NHS advises women to use pills with levonorgestrel, however, the study by researchers from the Leiden University medical centre in the Netherlands reveals, more harmful, third-generation, brands are being widely used.

The study says, contraceptive pills increase a woman's risk of venous thrombosis five-fold compared with non-users, though researchers stress absolute risk of blood clots due to using any type of oral contraceptives by young women is low, affecting less than one in 1,000 users and recommend a low-dose combined pill.

Over 100-million women worldwide use the pill, but have to put up with painful periods, fluctuating weight and mood swings, because doctors prescribe Pills not best tailored to their needs.

Besides, 23-brands of Pill, there are 14-types of female contraceptives, ranging from intrauterine devices to patches, implants and injections that slowly release hormones. A patch lasts a week, an injection eight or twelve weeks, while an implant lasts three years.