Studies have found that the usage of hormonal contraceptives increases the chances of thrombosis by 300 to 500 per cent. Isn’t it worrying? Definitely, it is worrying, but what is the absolute risk here?
Breaking news of the 60s
The association between certain types of oral contraceptives (that contain estrogen and progestin) with thrombosis has been known since the 1960s. Naturally, it led to attention from the media and panic in society, eventually to reduced usage and increased pregnancies.
A case of bad science reporting?
Hopefully, you have recognised the main issue with this report (remember the posts about covid vaccines and colorectal cancer.). A paper published in 2011 reviewed this case of thrombosis with root causes and relative risks. Among them was the absolute risk or the incidence of thrombosis for adults. It is 1 -10 per 100,000 per year. With the use of this type of oral contraceptive, the risk increase to 5 – 50 in 100,000 per year, which is up to 0.05%. But what about mishaps due to actual pregnancies and abortions?
Finally, just how big is a 100% increase of a risk? Well, that depends on the absolute risk on which it is based!
Hormonal Contraception and Thrombotic Risk: A Multidisciplinary Approach: PEDIATRICS, 127(2), 2011
