Blood clot

On the 15th of March Germany joined a dozen of other countries, mostly in the EU, in suspending vaccination with the AstraZeneca vaccine after sporadic reports of blood clots among recipients. As a response, some medical professionals have highlighted what many users of birth control are painfully aware of: the much higher risk of blood clots related to hormonal contraception. 

The European Medicines Agency stated on March 10th that out of the close to 5 million people vaccinated with the AstraZeneca shot in the European Economic Area, there have been 30 reported cases of blood clotting. “The crazy thing is that, even if the correlation between the vaccine and blood clots were proved, it would amount to a rate of 0.007 out of 1000,” the Head of the Italian Federation of General Practitioners said, after being bombarded with inquiries from people nervous about getting the AstraZeneca shot. For comparison, he continued, “the birth control pill has a proven risk rate of 0.6 in 1000”. And he’s right. 

Whilst obviously not all people using birth control suffer from blood clots, most birth control pills increase the chance of developing blood clots by two to six times. Birth control pills as well as patches, rings, and some IUDs use the hormones estrogen and/or progestin to prevent pregnancy. Whilst estrogen is most commonly associated with the risk of blood clots, one type of progestin (drospirenone) was found to increase the risk of blood clots more than any other form of progestin. This type is found in the popular contraceptives YAZ, Yasmin, Syeda, Zarah and Loryna. The US Food and Drug Administration (FDA) issued a warning about several of these contraceptives, but none were pulled from the market.

Confirming the risk stressed by the Head of the Italian Federation of General Practitioners, the FDA estimates the risk of birth control users developing a serious blood clot to be 0.3 to 0.9 out of 1000, every year. According to 2019 data collected by the UN, 842 million people use hormonal contraceptives. That means between 252,600 and 757,800 people are at risk of blood clots by using birth control. Similar, and sometimes higher, risks of blood clots are found when estrogen is used by trans women as a part of hormone therapy for gender affirmation.

The list of other side effects related to hormonal birth control is long and exposes many ways in which the health of women and people assigned female at birth is sidelined in medicine. For now, the fuzz around the Astrazeneca vaccine reveals how gender bias plays into our risk perception: Apparently, risks are perceived to be much higher when not exclusively affecting users of hormonal birth control.