The most common formulation of birth control pills has been linked to a doubling of relative risk of heart attack and stroke, a new study finds.

A recent study found that vaginal rings and even skin patches had used the same combination of hormones that pose similar health risks.

This could be a tough pill to swallow. An estimated 250 million women worldwide are believed to use some form of hormonal contraception. Past research has suggested a link between the use of synthetic hormones to prevent pregnancy and an increased risk of stroke and heart attack.