Two popular birth control pills linked in media reports to the deaths of 23 Canadian women will not be recalled, and a national gynecologists' group says the contraceptives, Yaz and Yasmin, are safe.

The deaths, first reported on Tuesday by the CBC, were uncovered in reports filed with Health Canada about more than 600 adverse drug side effects. The women ranged in age from 14 to 44, and typically died from complications of blood clots within a few months of being prescribed one of the drugs.

Anyone can file an adverse-effect report, and it is impossible to determine from a report whether the reaction was the direct result of using the product. The reports do not attribute a death to a side effect. Health Canada provides a synopsis of reports in an online searchable database.

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"Adverse events are very different from attributable events, and [the latter] is the number you need," said Jennifer Blake, a gynecologist and CEO of the Society of Obstetricians and Gynaecologists of Canada, who described being bombarded with calls from concerned women after the news reports. "We are advising that there is no new data and … that the pills are safe and effective."

Responding to an inquiry from The Globe and Mail, a spokeswoman for Health Canada said the agency monitors the safety of contraceptive pills regularly and has no intention of pulling Yaz and Yasmin out of circulation.

"At this time, it is Health Canada's view that the benefits of Yaz and Yasmin continue to outweigh the risks, when used according to Health Canada's approved labelling instructions," Leslie Meerburg said, adding later: "The risk of blood clots with these products is well known, and is included in the drug label."

Whether these contraceptives, and their use of a newer synthetic hormone called drospirenone, make women more prone to blood clots than so-called "older generation" birth control pills has been a subject of debate.

Studies have differed, and Bayer AG, the German company that makes the drugs, has said they pose no greater risk of blood clots than other contraceptive pills, all of which have been found to elevate the risks.

Conversely, a safety review conducted by Health Canada in 2011 determined that the pills may be associated with a 1 1/2 to threefold increased risk of blood clots compared with other hormonal contraceptives. The U.S. Food and Drug Administration arrived at a similar conclusion.

Nevertheless, the elevated risks detected in some studies remain relatively small. The FDA analysis, for instance, found that about 10 in 10,000 women taking pills with drospirenone will get a blood clot or venous thromboembolism in a year, compared with six in 10,000 women using another pill.

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To put that in perspective, a Society of Obstetricians and Gynaecologists of Canada report on the topic said the risk of developing a blood clot in pregnancy can be as high as 29 in 10,000.

Bayer has paid hundreds of millions of dollars to settle thousands of lawsuits in the U.S. that alleged the pills are behind deaths, heart attacks, strokes, blood clots and gallbladder ailments. Bayer told its shareholders last year that the settlements could reach $1.2-billion (U.S).

In April, a judge in the Ontario Superior Court of Justice certified a class action lawsuit against Bayer. It is expected to be a bellwether for 13 other class actions across the country that have yet to be approved. Bayer has filed a motion to appeal the class action certification, and is slated to argue in court on Sept. 4.

Matthew Baer, a lawyer with Siskinds LLP, in London, Ont., that is taking the lead in the Ontario case, said more than 2,000 women have come forward and that likely many more who were taking Yaz or Yasmin died.

"I think there are a lot more," he said. "It is generally accepted by the doctors and experts I've talked to that 1 to 10 per cent of adverse [drug side effects] get reported to Health Canada. I think you have to assume that there is at least 200."