New research citing an increased risk of heart disease among women who take -- or who have ever taken -- birth control pills is reigniting debate over the true connection between the birth control drugs and cardiovascular ills.
Researchers from Ghent University in Belgium looked at 1,301 apparently healthy women between the ages of 25 and 55 who had previously used oral contraceptives, half of whom used them for 13 years or more. What they said they found was that women who had used the pills had an unexpected increase in the presence of artery-clogging plaque in key blood vessels supplying the brain and legs.
On average, the researchers said the women had a 20 to 30 percent increase in plaque for every 10 years they had taken oral contraceptives. They presented their findings at the American Heart Association scientific sessions in Orlando, Fla., on Tuesday.
But past research on the possible connection has been far from conclusive.
At least two recent studies have suggested such a link does not exist. One, a Swedish study published in August on the second- and third- generation oral contraceptives currently used by most women, showed that women who were currently on the pills and those who had modern pills did not have a higher risk of heart attack.
And researchers in the WISE study group at the Cedars-Sinai Research Institute in Los Angeles completed a study of 672 postmenopausal women in 2006 that showed that past oral contraceptive use not only didn't increase the chances of coronary artery disease, but actually protected women from such heart ills.
Lead author of the WISE study Dr. Noel Bairey-Merz conceded that her study looked at a different population -- postmenopausal women with an average age of 60.
But she said that current evidence does not suggest that women taking oral contraceptives have an increased risk of heart disease once they pass menopause.
"So that's an example of something you measure when women are 35 years old that doesn't always predict what they're going to be like when they're 65," she said.
Conversely, two earlier metaanalysis studies (those which compile the results of previous studies) suggest that the pill -- or at least the older versions of the pill -- are linked to an 80 percent to 200 percent increased risk of heart attack in women currently using them.
In light of this, some doctors say, the only sure conclusion that can be made is that the exact link between oral contraceptives and heart problems will likely continue to be a controversial one.
"This new Belgium study does not provide a definitive answer to the question of whether or not past oral contraceptive use actually increases the risk of having a heart attack," said ABC News Medical Editor Dr. Tim Johnson. "Other studies addressing this question are contradictory.
"So this is a situation where the old cliché is really true -- we need more study."
If one thing is for certain, it is that any relationship between oral contraceptives and heart ills would have direct implications for millions of women. According to the Centers for Disease Control and Prevention, oral contraceptives are the most common type of birth control, used by 11.7 million women.
Doctors have already known that oral contraceptives increased blood pressure and the risk of blood clots in women who took them -- a risk that is even higher in women who smoke.