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Birth Control Pills Increase Blood Clot Risk in Women with PCOS

young woman looking at birth control tablets

A new study in the Canadian Medical Association Journal found that women with polycystic ovarian syndrome (PCOS) have twice the risk of developing a blood clot when taking oral birth control.

One of the study researchers, Dr. Christopher McCartney, told Reuters: “For some women, [the risks] might be high enough to say we really shouldn’t use the pill, such as for women over 35 who smoke.”

PCOS affects 5-10 percent of women and occurs when there is an imbalance of the sex hormones: estrogen, progesterone and androgen. Some of the symptoms of this condition are cysts on the ovaries, irregular menstrual periods, extra hair growth as well as higher risk of obesity, hypertension and diabetes. According to Reuters, women with PCOS also have more risk factors for heart disease.

The study began in 2001 and involved 43,506 women with PCOS who were between the ages of 18 and 46. Researchers compared the health information from the women with PCOS with information gathered from 43,506 women without PCOS. They found the risk of blood clots for women on oral contraceptives with PCOS was double that of women without PCOS.

Other findings also indicated that women with PCOS were more likely to be obese – 33 percent more likely, in fact. McCartney told Reuters: “I really think [obesity] could be something that’s contributing to the risk.”

Doctors Warn About Blood Clot Risk with Drospirenone

The fact that oral contraceptives can cause blood clots in some women is not new news, however. The hormones in the newest generation of birth control pills containing drospirenone, such as Yaz, Yasmin and Ocella, have been linked to a higher risk of blood clots than older pills.

A 2011 study, also published in the Canadian Medical Association Journal, showed that drospirenone raises women’s blood clot risk by a stunning 40 percent. Another study that appeared in Contraception in October 2012 found that this hormone also increased the risk of hospitalization from venous thromboembolic events (VTEs), more commonly known as blood clots, by 77 percent.

The lead author of the Contraception study, Dr. Stephen Sidney, is director of Research Clinics at Kaiser Permanente Northern California. Science Daily quoted Dr. Sidney: “The growing number of studies showing an increased risk of venous thromboembolic events with drospirenone suggests that drospirenone-containing combined hormonal contraceptives should be used cautiously for women seeking hormonal contraception.”

Doctors say that these studies are not meant to encourage women to not take the contraceptives, but that the risks and benefits should be carefully weighed in high-risk women.

However, the dangers of these newer birth control pills, particularly Bayer’s Yaz and Yasmin and their generic counterpart, Ocella, have prompted some women and their families to file suit against the drugmaker. Plaintiffs and their families accuse Bayer of concealing the risks of blood clots – some fatal – and misrepresenting the risks and benefits of these drugs.

Michelle Llamas, Senior Content Writer
Written By Michelle Llamas Senior Writer

Michelle Llamas has been writing articles and producing podcasts about drugs, medical devices and the FDA for nearly a decade. She focuses on various medical conditions, health policy, COVID-19, LGBTQ health, mental health and women’s health issues. Michelle collaborates with experts, including board-certified doctors, patients and advocates, to provide trusted health information to the public. Some of her qualifications include:

  • Member of American Medical Writers Association (AMWA) and former Engage Committee and Membership Committee member
  • Centers for Disease Control and Prevention (CDC) Health Literacy certificates
  • Original works published or cited in The Lancet, British Journal of Clinical Pharmacology and the Journal for Palliative Medicine

3 Cited Research Articles writers follow rigorous sourcing guidelines and cite only trustworthy sources of information, including peer-reviewed journals, court records, academic organizations, highly regarded nonprofit organizations, government reports and interviews with qualified experts. Review our editorial policy to learn more about our process for producing accurate, current and balanced content.

  1. Huffington Post. (2012, December 3). Blood clot risk higher for women with polycystic ovarian syndrome who take birth control pill: Study. Retrieved from
  2. Grens, K. (2012, December 3). Hormone disorder and the pill tied to blood clots. Reuters. Retrieved from
  3. Science Daily. (2012, October 18). Elevated risk of blood clots in women taking birth control containing drospirenone.
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