A Surprising Way Birth Control Affects Your Health and Hormones

Birth control pills are a cornerstone of women's healthcare, offering freedom and control. But have you ever stopped to consider how they might be affecting your body beyond just preventing pregnancy?

Did you know they can influence more than just your fertility? We're here to shed light on the surprising ways birth control can impact your well-being. By understanding these effects, you can make informed choices about your health and navigate options that work best for you.

Hormones that dictate menstruation

Estrogen and progesterone

Most contraceptives combine estrogen and progesterone—two hormones that naturally fluctuate during a monthly cycle. Their levels help to dictate the maturation and release of an egg and the beginning of menstruation.



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Testosterone and sex hormone binding globulin (SHBG)

Testosterone is often considered only important for men; women also have it, though in much lower amounts. Adequate levels maintain muscles, bone strength, sex drive, and energy levels.

We can find this hormone either as bound or unbound in the body. We consider the former "free Testosterone." This is because it binds to albumin, a transport protein, in a relatively weak way.

On the other hand, you have only about 3% of truly free—unbound—testosterone in your body. 30–35% binds to albumin. One large meta-analysis found that total and free testosterone levels decline by roughly 30% and 60%, respectively, with the use of hormonal contraception.

Researchers think three mechanisms cause it:

1. The suppression of testosterone production by the ovaries
2. The hindering of testosterone production by the adrenal glands
3. Increased SHBG. [1]

» Learn more about critical biomarkers associated with female fertility

Birth control and sex hormone binding globulin

SHBG helps transport other sex hormones safely through the bloodstream. Your liver produces it in response to testosterone and estrogen. Since birth control includes a form of the latter, it makes sense that SHBG levels increase. In fact, studies suggest they might even rise as high as 250%. [1]

Elevated SHBG can be alarming, especially without a known explanation. Men experience it because of excessively high testosterone, overtraining, undereating, and inadequate sleep. These factors can also affect women but to a lesser extent.



The impact of different birth control forms on SHBG

Overall, intrauterine devices have the lowest impact on SHBG. They typically have lower hormone amounts and use different forms of estrogen and progestin, a synthetic form of progesterone.

On the other end of the spectrum, ring or patch contraceptives cause the highest increase in SHBG levels. Falling somewhere in between are oral pills.

The hormones used also impact the degree of rise in SHBG. Progestin—or progesterone-only medications are typically associated with the lowest impact. [3] Levonorgestrel—a synthetic hormone found in many contraceptives—is also associated with a low impact on SHBG.

The most used synthetic form of estrogen, ethinylestradio, results in a slight increase. Additionally, lower doses of this contraceptive have less of an effect. Clinicians typically define the threshold for a high amount by 50 ug or more.

Finally, forms including progestogens gestodene, desogestrel, cyproterone acetate, and drospirenone are all associated with higher SHBG levels. As always, talk to your doctor before changing or stopping any medications.



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Why should you care about SHBG?

Elevated SHBG can be a valuable marker to determine the risk for venous thrombosis or a blood clot. While deciding whether to use birth control is a personal decision, we at InsideTracker want to offer more information about a topic that doesn’t receive the attention it deserves but affects many.



Making informed birth control decisions

There are many forms of birth control available. Our review doesn't include every available form, but we do include some of the main ones. In summary, levonorgestrel, progestin/progesterone, or IUDs appear to have the lowest impact on SHBG levels.

Pills containing only levonorgestrel or progestin/progesterone followed, followed by "low dose" ethinylestradiol. Lastly, high doses of ethinylestradiol, the ring, and the patch are associated with the highest increase in SHBG levels.

Impact on SHBG is undoubtedly not the only factor when deciding on a birth control method. Still, these insights can help you make a more informed decision or help to explain an elevated SHBG level.

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Beyond family planning

The impact of birth control goes beyond just preventing pregnancy. By understanding these effects, you can have a more informed conversation with your doctor when choosing a birth control method that best suits your individual needs.

Remember, there's no one-size-fits-all approach. With knowledge and open communication with your physician, you can find the option that empowers you to manage your health and achieve your personal goals.

As part of our onboarding questionnaire, InsideTracker Ultimate Plan asks about hormonal contraceptive use to help determine optimal blood biomarker zones and offer the best recommendations to our users.

References

[1] Raps, M., Helmerhorst, F., Fleischer, K., Thomassen, S., Rosendaal, F., Rosing, J., Ballieux, B. and Van Vliet, H., 2012. Sex hormone‐binding globulin as a marker for the thrombotic risk of hormonal contraceptives. Journal of Thrombosis and Haemostasis, 10(6), pp.992-997.

[2] https://www.cdc.gov/nchs/fastats/contraceptive.htm

[3] Hugon-Rodin, J., Alhenc-Gelas, M., Hemker, H.C., Brailly-Tabard, S., Guiochon-Mantel, A., Plu-Bureau, G. and Scarabin, P.Y., 2017. Sex hormone-binding globulin and thrombin generation in women using hormonal contraception. Biomarkers, 22(1), pp.81-85.