Is there an increased risk of stroke associated with oral contraceptives?

Abstract

In the last few years several studies were published about the relationship between oral contraceptive use, estrogen dose, different types of progestogens, cigarette smoking and the risk of stroke. There is a persistent association between the use of oral contraceptives containing more than 50microg of ethinylestradiol and the risk of stroke. Also, cigarette smoking seems to be a strong additive risk factor, especially in women >35 years old even with lower doses (< or =30microg) of estrogen. Unlike oral contraceptives containing >50microg of estrogen, currently there is no convincing evidence that the use of oral contraceptives containing <50microg in the absence of smoking is associated with any meaningful increase in the risk of ischaemic or haemorrhagic stroke. Progestogen-only pills are not associated with an increased risk of stroke. A specific type of progestogen in combined pills was associated with an increased risk of stroke in a few studies. Data regarding this issue is, however, inconsistent and controversial and needs further investigation. There were few if any studies that have addressed the effects of new types of progestogens (i.e. norgestimate, norgestrel or gestodene) and formulations containing 20microg of ethinylestradiol. At the present time we find no reason to alter the current practice in prescribing oral contraceptives. We do concede, however, that there might be a slight causal relationship between use of oral contraceptives containing <50microg of ethinylestradiol and stroke that did not reach statistical significance. This relationship is rare and should be viewed in context with the many benefits of oral contraceptives. Underlying risk factors for stroke such as factor V Leiden mutation and other thrombophilias might explain the role of oral contraceptive-induced stroke.