Use of oral contraceptives and postmenopausal hormone replacement: evidence on risk of stroke.

Estrogen and progesterone affect endothelial function, coagulation factors, platelet function, lipids, and inflammation and have neuroprotective effects in experimental animals. Oral contraceptives containing low-dose estrogen increase the risk of ischemic stroke, but the absolute risk is low. Risk factors further increasing the risk of stroke in users of oral contraceptives include smoking, hypertension, diabetes, hyperlipidemia, migraine with aura, and thrombophilia. Progestin-only contraceptives do not increase the risk of stroke and are preferable in women with cerebrovascular disease or risk factors. Hormone replacement therapy (HRT) with estrogen alone or combined with progesterone increases the risk of ischemic stroke by 40% with no effect on hemorrhagic stroke. Stroke risk increases with the dose of estrogen. The time between menopause and the initiation of HRT does not influence ischemic stroke risk. The only indication for HRT is the treatment of vasomotor symptoms; if needed for this purpose, the lowest dose of estrogen should be used for the shortest possible duration.