Female athletes who are long-term oral contraceptive pill users have up to five times the amount of a marker identifying cardiovascular disease risk than those not on the pill, says new Brock-partnered research.

Taking the pill for more than a year increases basal levels of C-reactive protein (CRP), a protein that raises the risk of inflammation and cardiovascular conditions, which could lead to heart attacks, strokes and other diseases, says the study’s senior author Toby Mündel.

The Professor of Kinesiology at Brock University says the risk is over the long term and does not necessarily present an immediate danger.

“For most people, it’s less of a singular event like a heart attack or a stroke,” he says. “It’s more like a build-up where, at some point in your life, you’re going to be told by a doctor, ‘hang on, you need blood pressure medication.’”

The study, “Does chronic oral contraceptive use detrimentally affect C-reactive protein or iron status for endurance-trained women?,” compared eight naturally menstruating females and eight females who had been continuously taking the monophasic combined oral contraception pill for more than 12 months.

Monophasic pills contain the same amount of synthetic estrogen and progesterone throughout the four-week cycle, with one week of placebo or sugar pills.

The research team, which included first author Claire Badenhorst from Massey University of New Zealand and Andrew Govus at La Trobe University in Australia, ensured the two groups of females had identical diet and exercise routines that meant they were well rested.

At certain points during the menstrual cycle, the researchers gathered and tested blood and urine samples from all participants.

“We found that according to their blood CRP levels only one out of the eight females who had a normal menstrual cycle had an intermediate risk of cardiovascular disease, whereas in the group of females taking the oral contraceptive pill, five out of the eight females had an intermediate risk, and two were at a high risk of cardiovascular disease,” says Mündel. “Some might see these results as counter-intuitive, since exercise protects against cardiovascular diseases.”

Mündel notes that the body produces CRP, found in blood plasma, as low-grade inflammation. He says researchers are unclear about how and why the oral contraceptive pill brings about inflammation.

“One of the thoughts is that oral contraceptives contain synthetic hormones, which may not have the protective effects of naturally occurring estrogen,” he says, adding that some scientists say synthetic hormones could trigger “something negative” that affects cells lining blood vessels.

Mündel recommends that female athletes deciding whether or not to take the oral contraception pill view his team’s research findings in a larger context, especially for females prescribed the pill for reasons other than contraception.

“There are real advantages and benefits from taking the contraceptive pill, be it for birth control at a certain stage in their career or to control heavy menstrual bleeding and other negative conditions,” he says. “People need to be informed of any consequences as they determine the balance between risks and benefits.”