Introduced in the 1960s, oral contraceptives have been used by about 80 percent of women in the United States at some point in their lives.
For women without pre-existing risks for heart disease, the early formulations were generally safe, and the newer ones appear to be even safer, but all the risks and benefits are yet to be established, especially as women's lifestyles change and new forms of contraceptives become available, according to specialists in women's heart disease at Cedars-Sinai Medical Center.
"As women use these therapies more frequently and for longer periods of time, there is an urgent need to better understand and minimize associated cardiovascular risks," said C. Noel Bairey Merz, M.D., director of the Women's Heart Center and the Preventive and Rehabilitative Cardiac Center at the Cedars-Sinai Heart Institute. She is senior author of an article in the Jan. 20, 2009, issue of the Journal of the American College of Cardiology that provides an overview of the known cardiovascular risks and benefits of hormonal contraceptives while pointing out areas that require further research.
Reproductive hormones affect the tone and function of blood vessels as well as lipid (fat) levels in the blood. Low estrogen levels have been found to increase risk of coronary atherosclerosis (thickening and hardening of artery walls) and "adverse cardiac events," such as heart attacks and strokes. But the use of supplemental estrogen in hormone replacement therapy has been linked to an elevated risk of blood clots that can lead to heart attacks and strokes.
"Health care providers must evaluate each woman's risk factors, especially those related to cardiovascular health, prior to starting any contraceptive therapy. Although pre-menopausal women have a much lower risk of cardiovascular disease, routine screening for potential problems and follow-up is important," said Chrisandra L. Shufelt, M.D., assistant director of the Women's Heart Center at the Cedars-Sinai Heart Institute and co-author of the journal article.
The earlier contraceptives used higher levels of estrogen than the newer formulations, which are now available not only in pill form but in patches and vaginal rings. The newer formulations use lower doses of estrogen, which is safer in terms of lowering the risk of blood clots, and they tend to use a progestin, a synthetic version of progesterone that is not likely to raise blood pressure and may even slightly reduce it, according to Bairey Merz, who holds the Women's Guild Endowed Chair in Women's Health and is a professor of medicine at Cedars-Sinai.
Since 2000, death rates have increased in women between the ages of 35 and 44, while all other age groups have seen a decline. Among factors that may be contributing to the rise are increases in obesity and smoking, a decline in physical activity at this time in life, and a significant increase in the use of oral contraceptives.
Women at high risk for cardiovascular problems, especially those who smoke, should consider alternative forms of contraception. Those with other cardiac risk factors, such as hypertension or elevated cholesterol, can consider using hormonal contraceptives if they are carefully monitored by their health care provider, Bairey Merz said.
Any woman considering the use of contraceptives should be evaluated for cholesterol levels, blood pressure, smoking, diabetes, kidney problems, obesity and other vascular diseases, including migraines. Healthy, nonsmoking women who are 35 or older can continue taking a low dose oral contraceptive until 50 to 55 years after reviewing the risks and benefits.