No Link Found Between Low-Dose Contraceptives And Stroke Risk

November 05, 1998

DALLAS, November 6 -- Women taking low-dose oral contraceptives are not at a greater risk of having a stroke, say researchers in this month's Stroke: Journal of the American Heart Association.

Ever since "the pill" was introduced in the United States in the 1960s, there has been concern about the potential increased risk of heart attack and stroke associated with taking oral contraceptives. According to the study's author, earlier research showed a significant -- three to five-fold -- increase in stroke risk in women taking oral contraceptives.

A new formulation of contraceptive -- one with less estrogen and less progestin -- has been prescribed increasingly since the 1980s. It's been unclear, say the researchers, whether these new formulations posed a risk for stroke. Researchers pooled results of two studies -- one in California and one in Washington -- involving 373 women between the ages of 18-44 who had a stroke and 1,191 women of similar age who had not had a stroke.

Compared to women who were not using oral contraceptives, women currently using low-dose formulations of "the pill" had only a 9 percent higher risk of an ischemic stroke, which occurs when blood flow to the brain is stopped by a blood clot or clogged vessel. In particular, there was no increased risk among women who didn't smoke or have high blood pressure.

When the researchers looked at the risk of hemorrhagic stroke -- a stroke caused by bleeding in the brain and more common in younger women than older women -- risk was increased only 11 percent. "We feel that neither of these increases is a statistically important difference," says the study's lead author, Stephen Schwartz, Ph.D., University of Washington School of Public Health, Seattle.

In some of their analyses, the researchers found that users of oral contraceptives were at lower risk of stroke than women who had not used "the pill." One likely explanation, Schwartz says, is that doctors tend to prescribe these pills to women who are already healthy.

The results are similar to an earlier study the researchers published in the September 15 issue of Circulation: Journal of the American Heart Association on heart attack risk associated with oral contraceptive use. That study showed there was not a link found between heart attack risk and low-dose oral contraceptives. The scientists say that strokes and heart attacks are both rare in young women, occurring in fewer than 2 out of every 10,000 women each year in the populations involved in this study.

"For both heart attack and stroke, there is pretty convincing evidence that women who do not have other cardiovascular disease risk factors -- smoking, high blood pressure, obesity -- are not at increased risk if they use low-dose contraceptives," Schwartz says. "There still remains the question of whether certain subgroups at risk for stroke -- smokers, those with high blood pressure -- are at increased risk when low-dose oral contraceptive use is added."

"It's relatively rare for a woman who smokes or has high blood pressure to be prescribed oral contraceptive pills in the United States," he adds. "For this reason, the ability to assess risks in these groups in this study was very limited. It does point to the need to do more thorough research on certain subgroups of women who might be more susceptible to strokes when using oral contraceptives."
Co-authors include Diana B. Petitti, M.D.; David S. Siscovick, M.D.; W.T. Longstreth, Jr., M.D.; Stephen Sidney, M.D.; Trivellore E. Raghunathan, Ph.D.; Charles P. Quesenberry, Jr., Ph.D.; and Joseph Keleghan, M.D.

American Heart Association

Related Heart Attack Articles from Brightsurf:

Top Science Tip Sheet on heart failure, heart muscle cells, heart attack and atrial fibrillation results
Newly discovered pathway may have potential for treating heart failure - New research model helps predict heart muscle cells' impact on heart function after injury - New mass spectrometry approach generates libraries of glycans in human heart tissue - Understanding heart damage after heart attack and treatment may provide clues for prevention - Understanding atrial fibrillation's effects on heart cells may help find treatments - New research may lead to therapy for heart failure caused by ICI cancer medication

Molecular imaging identifies link between heart and kidney inflammation after heart attack
Whole body positron emission tomography (PET) has, for the first time, illustrated the existence of inter-organ communication between the heart and kidneys via the immune system following acute myocardial infarction.

Muscle protein abundant in the heart plays key role in blood clotting during heart attack
A prevalent heart protein known as cardiac myosin, which is released into the body when a person suffers a heart attack, can cause blood to thicken or clot--worsening damage to heart tissue, a new study shows.

New target identified for repairing the heart after heart attack
An immune cell is shown for the first time to be involved in creating the scar that repairs the heart after damage.

Heart cells respond to heart attack and increase the chance of survival
The heart of humans and mice does not completely recover after a heart attack.

A simple method to improve heart-attack repair using stem cell-derived heart muscle cells
The heart cannot regenerate muscle after a heart attack, and this can lead to lethal heart failure.

Mount Sinai discovers placental stem cells that can regenerate heart after heart attack
Study identifies new stem cell type that can significantly improve cardiac function.

Fixing a broken heart: Exploring new ways to heal damage after a heart attack
The days immediately following a heart attack are critical for survivors' longevity and long-term healing of tissue.

Heart patch could limit muscle damage in heart attack aftermath
Guided by computer simulations, an international team of researchers has developed an adhesive patch that can provide support for damaged heart tissue, potentially reducing the stretching of heart muscle that's common after a heart attack.

How the heart sends an SOS signal to bone marrow cells after a heart attack
Exosomes are key to the SOS signal that the heart muscle sends out after a heart attack.

Read More: Heart Attack News and Heart Attack Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to