According to a new study published in the British Medical Journal on May 10, 2016, with the same dose of oestrogen, two different progesterone types (desogestrel and gestodene) have been significantly associated with higher risks of formation of blood clots in women’s lungs. however, this risk lowers when estrogen dose is reduced with same dose of progesterone.

The study was conducted at the French National Health Insurance (Department of Studies in Public Health) and French National Agency for Medicines and Health Products, at the official request of the French Ministry of Health.

The research was funded by the French National Health Insurance Fund (CNAMT) and the French National Agency for Medicines and Health Products Safety (ANSM) whilst the authors did not disclose any conflicting interests.

The study that included 5 million French women also found that when adjusted for the same types of progesterone an oestrogen dosage of 20 ug compared to 30-40 ug was associated with lower risks of ischemic stroke, myocardial infarction and pulmonary embolism.

Moreover, combined oral contraceptive associated with the lowest risk of pulmonary embolism and arterial thromboembolism was the one with levonorgestrel containing 20 ug of oestrogen.

However, the associations of oral contraceptives with the risk of embolisms, heart attacks and stroke are already known, along with the association of a dose related effect of oestrogen with multiple progestogens (gestodene, levonorgestrel, and desogestrel) resulting in increased risks of venous thromboembolism. Therefore, this study provides welcome insights into the dose levels that are associated with lower risks of these diseases.

The observational cohort study worked with the data of 5,443,916 women and its criteria included years of pill contraceptive use, 1,800 pulmonary embolisms, 407 myocardial infarctions, and 1,046 ischemic strokes. The women were all residents of France during the period of July 2010 and September 2012.

The mean age of the women in the study was 28 and almost 34%of the women used oral contraceptive with 20 ug oestrogen.

The four most commonly used combinations were 30-40 ug estrogen with levonorgestrel (55.3% women), 20 ug estrogen with levonorgestrel (15.3% women), 20 ug of estrogen with desogestrel (13.9%), and 30 ug estrogen with desogestrel.

In United Kingdom, 28% of the women of reproductive age (between ages of 15 to 29) use oral contraceptive pills whereas 17.1% of the women of the same age use these pills in Unites States. In the US, 900,000 people develop blood clots each year, of which 100,000 (274 per day) die.

A combined oral contraceptive pill contains artificial female hormones oestrogen (or estrogen) and progesterone, which are naturally present in women’s bodies as well. By taking the pill, the production of women’s eggs from ovaries (ovulation) can be controlled by moderating the production of Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH). This, in turn, helps prevent a pregnancy.

The pill can also make it harder for a sperm to reach the egg by thickening the mucus at the entrance of the womb, through the action of synthetic progesterone, which can also help preventing unwanted pregnancies.

This pill is often used for treating heavy periods, painful menstruation, premenstrual syndrome (PMS) and endometriosis. When taken correctly, the pill can be effective in preventing unwanted pregnancies 99% of the times.

The pill also comes with certain disadvantages. According to the National Health Services (NHS), UK, oestrogen pills can cause the blood to clot more readily. If that happens it can lead to deep vein thrombosis (clot formation in the veins of your leg), pulmonary embolism (clot in the lungs), myocardial infarction, or a stroke.

Physicians are advised to inspect if a female is at risk for developing these conditions before prescribing the combined oral contraceptive drug. The conditions can include:

  • being 35 years of age or above
  • being smoker or a recent quitter
  • a woman with a BMI of thirty five or above
  • migraines with aura or a warning sign
  • high blood pressure or hypertension
  • history of blood clots and strokes
  • a close relative with a history of blood clot before the age of 45
  • being immobile (in a wheel chair, or prolonged rest due to an injury)

Understanding Pulmonary Embolism Risk

A recent partnership between the National Blood Clot Alliance (NBCA) and Alexandra L Rowan Memorial Foundation in United States is running a Thunderclap Campaign on social media channels in an attempt to focus on unique blood clotting risks of women during the National Women’s Health Week (NWHW),. This program, which is being run from May 8-14, can help women understand and become more aware of their reproductive decisions.

This particular program recognizes the increased risk women go through for embolisms when making certain crucial reproductive choices such as threefold increased risk for blood clots by estrogen based pills, threefold increased risk due to hormone replacement therapies, fourfold increased risk during pregnancy, and hundredfold increase of risk of embolisms in the week immediately following the delivery.

“We need to sound the alarm and increase awareness about blood clot risks unique to women, particularly as they relate to estrogen-based birth control,” says David Rowan, head of the Rowan Foundation.”

Finally, research conducted by the American Public Health Association shows that only one quarter of the public is aware of deep vein thrombosis (DVT) or blood clots while research from NBCA shows that only 10% of the people had any knowledge of DVT and pulmonary embolism in the United States.