Birth control pills may lower women's risk of certain cancers and heart disease, according to two new studies from Wayne State University.

The studies, which were presented in Philadelphia at the annual meeting of the American Society for Reproductive Medicine (search), used data from the Women's Health Initiative (search) study.

More than 160,000 women participated in the Women's Health Initiative, including about 67,000 who had used birth control pills (search) in the past.

The data were analyzed by researchers including Rahi Victory of the obstetrics-gynecology department of Wayne State University's medical school.

In light of recent concerns about hormone replacement therapy, the scientists wanted to see what, if any, effect birth control pills had on cancer and heart disease risks.

Birth control pills are formulated differently from hormone replacement therapy and were not addressed in the Women's Health Initiative.

Birth Control Pills and Heart Disease

With regard to heart disease, the researchers found "highly significant relationships" between birth control pills and reduced risk of a wide range of problems including cardiovascular disease (search), high cholesterol, high blood pressure, heart attack, and stroke. The risk reductions were generally seen in women who had taken birth control pills for more than one year.

However, the reduced risk for angina (search) (chest pain), transient ischemic attack (a mini-stroke), and certain blood vessel diseases was only seen in women who had used birth control pills for more than four years.

The data showed, however, that increasing age, elevated body mass index, and smoking greatly increased the risks of cardiovascular events, even in birth control users.

Oral Contraceptives and Cancer

Though the study initially showed significant relationships between birth control pills and many types of cancer, after controlling for risk factors that contribute to these cancers, "there was no effect on risk of breast cancer, bladder cancer, or colon cancer," they say.

However, the data did show that women who had used birth control pills for a longer period of time did have reduced risks for endometrial cancer (cancer of the lining of the uterus) and ovarian cancer.

As with heart disease, older women and those with diabetes consistently had increased risks for any cancer, endometrial cancer, and ovarian cancer.

The Pill Has Many Varieties

Many different birth control pills have hit the market since the first one debuted in 1960.

The formulations used today are different from those in the past, which may be one reason why studies over the years have yielded contradictory findings, for better or worse, on the health impact of birth control pills.

Expect further research on the topic.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCE: 60th Annual Meeting of the American Society for Reproductive Medicine, Philadelphia, Oct. 18-20, 2004. WebMD Medical Reference from Healthwise: "Transient Ischemic Attack (TIA): Topic Overview." WebMD Medical News: "Four Decades of the Birth Control Pill." WebMD Feature: "A History of Birth Control."