Oral contraceptives (OCs) no longer pose the higher risk of heart attack for women they once did, a recent investigation concludes.

The 48,321 women in the study were between age 30 and 40 years. They lived in Sweden in 1990-91 and were participating in a larger project. Using data collected over the next 11 years, researchers analyzed how OC use affected the likelihood of MI.

Most of the women who used an OC were taking low-dose estrogen as well as second- or third-generation progestins. Compared with women who had never used an OC, neither former OC users (relative risk 1.0) nor current OC users (0.7) had a raised risk of future MI when any other risk factor was analyzed, the researchers found (Fertil Steril. 2007;88:310-316). Those factors included age, smoking, BMI, hypertension, and diabetes.

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“There has been very little research since newer forms of pills containing lower doses of estrogen have become the standard of care,” noted lead author Karen Margolis, MD, MPH, of the HealthPartners Research Foundation in Minneapolis. “Our research suggests that women who use modern types of OCs in their 30s and 40s do not have an increased risk of heart attack compared to nonusers.”

Although the project used a Swedish sample, the finding should apply to American women. “The OCs may have different names, but they are quite similar to what we have here,” she said.The study also found a fourfold MI risk among the 25% of participants who were smokers. OC use didn’t seem to affect that risk. Still, Dr. Margolis warned, “because relatively few women had heart attacks—214 out of 48,000 women followed for 11 years—I would hesitate to put as much faith in this result: I would still be cautious about using OCs in smokers.”