Birth control pills reduce the incidence of heart attacks and other forms of cardiovascular disease and lower the incidence of certain types of cancer, including ovarian and endometrial cancer, researchers said Wednesday.
A team from Wayne State University in Detroit used the massive data available for 162,000 women in the Women’s Health Initiative – the same study that showed that hormone replacement therapy was much riskier than previously believed – to provide the most definitive word yet on the safety of the pill.
Previous smaller studies looking at the link between the pill and cardiovascular disease have come down on both sides of the issue, with some showing a risk and some showing a benefit. Overall, said Dr. Michael Diamond of Wayne State, the consensus was that the hormones in the pill – estrogen and progestin – increased the risk of heart disease.
The new findings, he added, should be “very reassuring” for women taking the pill.
The team presented the results in Philadelphia Wednesday at a meeting of the American Society for Reproductive Medicine.
An estimated 16 million American women are currently on the pill and many times that number have taken them since their introduction in 1960.
The Women’s Health Initiative included 62,000 women who had taken the pill at one time or another. Diamond, Dr. Rahi Victory and their colleagues used the data to compare health effects for those women to those who had not taken it.
They found that the hormones reduced the risk of hypertension, heart attacks, strokes, aneurysms and high cholesterol levels by 8 percent to 10 percent, Diamond said. It reduced the need for surgical procedures, including angiograms and bypasses, by 20 percent to 50 percent.
The longer the women took the pill, he added, the greater the reduction in risk.
Smoking negated many of the beneficial effects of the pill, he said, but smokers who took it still had a lower risk than smokers who did not.
Overall, women who took the pill had a 7 percent lower risk of cancer. Those who took the hormones for four years or longer had a 42 percent lower risk of ovarian cancer and a 30 percent lower risk of uterine cancer, he said.
The researchers found no effect on the incidence of other cancers, including breast, colon and bladder tumors. That is actually a positive finding, Diamond said, because some studies had suggested that the pill increased the risk of breast cancer.
The researchers are not sure how the pill confers its benefits on users.