Birth-control pills tied to dangerous clots: Which brands?

Progestin-only contraceptives were listed as possible carcinogens.

(CBS/AP) Are newer birth control pills riskier than old ones?

Maybe so - new research from the FDA suggests newer birth control pills, including Bayer's Yaz, may lead to a greater risk for dangerous blood clots.

The FDA reviewed the medical histories of more than 800,000 women taking different birth control pills between 2001 and 2007. On average, women taking Yaz had a 75 percent greater chance of experiencing a blood clot than women taking older birth control drugs.

When a clot forms in a vein, part of the clot and travel to other parts of the body, and if a clot travels to the lungs or brain it can be deadly - a condition known as venous thromboembolism (VTE). Previous studies suggest women taking drospirenone-containing birth control are at a higher risk of developing VTE, while others have not reported this effect, the FDA said.

What's drospirenone? It's a female sex hormone that's found in newer contraceptive pills including Beyaz, Gianvi, Loryna, Ocella, Safyral, Syeda, Yasmin, Yaz, and Zarah, WebMD reported.

"Bayer is currently evaluating this publication and cannot comment at this point in time," Rose Talarico, deputy director of product communications for Bayer Healthcare, told CBS News in an email.

The agency also reports higher rates of complications in women using the Ortho Evra patch from Johnson & Johnson and Merck's Nuvaring vaginal ring.

The FDA has yet to reach a final conclusion on the newer pills' safety, but will hold a public meeting in December to discuss the findings from its study.

If the link is shown to be definitive, some safety critics think the FDA should share the blame for approving these pills, while cheaper generics with established safety records are widely available.

"At a certain point we have to ask why the FDA continues to approve drugs that are less safe and have no benefit compared to drugs already on the market," said Dr. Diana Zuckerman, president of the advocacy group, National Center for Women and Families. "With all these different birth control options, why take the most expensive one that can also kill you?"

What's the take-away message for women?

"I think women really need to talk with their doctors before they start a birth control pill, and doctors should try to choose ones that have lower risks," Dr. Jennifer Wu, an obstetrician/gynecologist at Lenox Hill Hospital in New York City, told WebMD. "I wouldn't start with these riskier oral contraceptives as first-line, first-start pills."

Planned Parenthood has more on birth control pills.