These conclusions appear to apply equally to women in developed and developing countries. Recent studies and most older ones have found that heart attack risk does not increase with duration of OC use. Planned Parenthood Federation of America Smoking increases the risk of heart attack and stroke especially for older women who use oral contraceptives. This US poster warns of the risk and urges pill users not to smoke. Thrombotic stroke, also called occlusive or ischemic stroke, occurs when the flow of blood in the brain is blocked.
Hemorrhagic stroke occurs when a blood vessel in the brain ruptures.
The most common stroke in women of reproductive age is subarachnoid hemorrhage, in which blood from the ruptured vessel enters the space below the brain's arachnoid membrane and spreads through cerebrospinal fluid passageways. The more recent studies provide more information on ischemic stroke than on hemorrhagic stroke. Lower doses appear to have reduced the risk. The multicenter WHO study the largest case-control study of stroke and OCs by far found an overall relative risk of ischemic stroke of about 3 among OC users. Current OC users who did not smoke, had their blood pressure checked, and did not have high blood pressure were at 1.5 times greater risk than nonusers.