THE ESSENTIAL
- Covid-19 – especially the severe forms – can increase the risk of thromboembolic events, such as thrombosis and/or pulmonary embolism.
- The global prevalence of obesity almost tripled between 1975 and 2016 according to the WHO: 15% of adult women are obese.
There are 50,000 to 100,000 cases of phlebitis – or venous thrombosis – per year in France, according to National Institute of Health and Medical Research (Inserm). This is the formation of a blood clot in a vein. Most often, it is the lower limbs that are affected, either in a deep vein, which is then called deep phlebitis, or in a superficial vein, which is then called superficial phlebitis or paraphlebitis. One of the serious complications can also be a pulmonary embolism.
Venous insufficiency and hypercoagulability
Among the risk factors, there is first of all venous insufficiency which means that the venous network is not efficient enough and that the blood has trouble circulating normally. Then there is hypercoagulability, that is, the formation of a clot by imbalance of the blood coagulation system. This can be due to a genetic predisposition, smoking, obesity or even pregnancy. Some medications also increase this risk.
“We deplore each year 0.5 to 1 case of thrombosis for 10,000 women without hormonal contraception, can we read on the Inserm website. This risk increases to 2 per 10,000 women on the first or second generation pill (…) and 4 per 10,000 women on the third and fourth generation pill”. And the risk would be even greater for obese women, according to a study published in the journal ESC Heart Failure.
A risk of thrombosis associated with estrogen-progestogen pills
Researchers have established that obese women who use birth control pills containing estrogen and progestins – two hormones present in most marketed pills – have a 24 times higher risk of developing venous thrombosis compared to women with normal weight and do not take this type of contraceptive. For overweight women, this risk was 12 times higher. On the other hand, pills containing only progestins are not associated with a greater risk of venous thrombosis.
“It is well established that obesity and contraceptives containing estrogen are risk factors for venous thrombosis, explains Giuseppe Rosano, one of the authors of the study. Despite this, obese women continue to receive these drugs. Scientific evidence indicates that obesity and oral contraceptives [contenant des œstrogènes et des progestatifs] have a synergistic effect on the risk of developing venous thrombosis and this should be considered in prescribing decisions“.
Obese women under 40 are most at risk
The authors therefore hope that their study will make it possible to change the prescription and to introduce new habits to women who take this type of contraception. “The risk is particularly high in obese women under the age of 40, because it is at this age that many take contraception, concluded Giuseppe Rosan. Obese women using contraceptives are at higher risk of developing venous thrombosis and should take steps to limit their other predisposing factors for cardiovascular disease, such as quitting smoking and increasing their level of physical activity”.
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