Frequently our patients ask us about the risks of taking birth control pills and if certain pills are riskier than others. The media has scared many people by reporting that pills such as Yasmin are dangerous, and it is important to understand the facts.
The risk of blood clots, which can be life threatening, is known to be increased on birth control pills and some other forms of hormonal contraception. Such blood clots usually form in the deep veins of the legs causing localized pain and swelling (called a DVT or deep vein thrombosis), but if pieces of the clot break off and travel to the lungs (a pulmonary embolus) or the brain (a stroke) this can be life threatening.
Studies show that certain pills (including Yasmin, Yaz, Beyaz, Desogen, Mircette, Cyclessa, Gianvi, Loryna, Ocella, Zarah, Kariva, Othocept, Emoquette and Velivet) have a slightly higher blood clotting risk than other pills. Non-oral forms of hormonal birth control including Nuvaring and the OrthEvra patch also have a slightly higher blood clotting risk than some oral pills.
The important thing to understand is that the risk of a life threatening blood clot on any form of hormonal birth control is very small, and that in most cases, the benefits of the pill outweigh the small risk. In fact since hormonal birth control prevents pregnancy, and pregnancy bears a much higher blood clotting risk than any form of birth control, simply not becoming pregnant reduces the risk of blood clotting for the majority of women on hormonal birth control.
All birth control pills contain two hormones; an estrogen and a progestin. All pills contain the same estrogen component (although the dose of estrogen differs between pills and can be “low dose” or “high dose”). The part that differs between pills is called the progestin component, and the slight differences in blood clotting risk between pills seems to be dependent on this component.
Pills containing the newer progestins including drosperinone (in Yasmine, Yaz, Beyaz and their generics) and desogestrel (in Desogen, Mircette, Cyclessa and their generics) have a slightly higher blood clotting risk than pills containing the older progestin called levonorgestrel. It is not understood why the non-oral forms of hormonal birth control (which don’t contain these newer progestins) have a slightly higher clot risk than levonorgestrel pills.
Two recent large studies each looking at over a million women on hormonal birth control over a 10 or 15 year period both showed similar results. The results were reported as the likelihood of an event for 10,000 women aged 15-49 over a year’s time. For example, these studies showed that for every 10,000 women aged 15-49, between 2-4 women who had never used any hormonal birth control developed a blood clot over a year’s time.
For women on a levonorgestrel containing pill the risk approximately doubled, to 6-7.5 out of 10,000 women over a year’s time. For women on pills containing the newer types of progestin (including Yasmin, Yaz and Desogen) the risk increased to 10 blood clots for every 10,000 women over a year’s time. The risk of clot with Nuvaring was 8 per 10,000 women per year, and for the patch was 10 per 10,000 annually. Women using the Mirena IUD had no increase in blood clotting over baseline.
While the blood clotting risk is important to consider, to keep these numbers in perspective, the incidence of blood clot in pregnancy and the immediate postpartum period is double that of the highest risk on pills. Also, of all blood clots reported, only about 1/4 were in the lungs or brain (acutely life threatening) and 3/4 were in a limb and were treated before becoming acutely life threatening, so the incidence of death or serious injury was extremely small.
Women with an increased risk of blood clot such as smokers over 35, morbidly obese women and those with a personal history of blood clot or a hereditary blood clotting disorder are often advised not use hormonal birth control as the risk of clot may outweigh the benefits. But for women with an average risk of blood clot there are a number of benefits of hormonal birth control that often outweigh the very small risk. These include pregnancy prevention, reduction in ovarian and uterine cancer risk, and reductions in menstrual blood loss, period pain, breast pain and ovarian cyst formation. Other quality of life improvements such as acne reduction, mood stability and menstrual predictability also need to be taken into account.
When choosing a birth control method we think it is important to pick one that you like, since you are more likely to be compliant. Some of our patients love Yasmin for example, as is great for their acne and moods and doesn’t cause them to gain weight. Others love the ease of Nuvaring and enjoy not having to remember to take a pill every day. Since pregnancy prevention is usually one of our primary goals, choosing a product that you like and will take reliably is more likely to achieve that goal.
Because the real difference in blood clotting risk between products is very small, this is rarely the main factor that we think about when prescribing a birth control product. But for first time users with no particular preferences, we generally will suggest a pill with the lower clot risk profile, all else being equal.
If you have questions about your particular birth control product, please talk to your provider!
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