This Is Your Brain on Birth Control: The Surprising Science of Women, Hormones, and the Law of Unintended Consequences
By Sarah E. Hill, PhD
Many women have been on a birth control pill at some point in their lives. Sarah E. Hill, PhD, is a researcher who has dedicated her career to evolutionary psychology. She herself was on birth control pills throughout her young adult life, as she pursued her academic degrees and launched her career. In This Is Your Brain on Birth Control, she recounts how she realized in retrospect that when on birth control, she seemed like a less vibrant version of herself. After cutting the birth control method out, she noticed that she experienced increased energy, heightened sexuality and even a renewed interest in music, which she had loved as a teenager but had ignored throughout her twenties.
After first coming across a study that linked women’s romantic partner choices and sexual satisfaction with their pill-taking status, she then learned that women on birth control pills seem to be missing a key feature of their stress response. At that point, Dr. Hill realized that she had bumped right into the proverbial tip of the iceberg, and she began investigating all of the myriad ways that birth control pills (there are dozens on the market) can interfere with women’s biological makeup.
Our body’s hormones are an intricately balanced symphony, so it should not be surprising to recognize that taking a drug designed to rearrange a woman’s monthly cycle drastically might throw other things off-kilter as well. However, few doctors give women any sort of primer on the potential side effects of birth control pills. In many cases, the prescriptions are handed out without so much as a warning. In my case, I was given a prescription for a birth control pill when I wasn’t even sexually active (nor planning to be). The doctor’s rationale? My periods were three weeks apart (something I now realize was not abnormal), and the pill “might” reduce cramps and symptoms of premenstrual syndrome. The doctor never mentioned any potential downsides.
While the possible downsides are many and comprise a large portion of the book, Dr. Hill is quick to state—and repeat—that she does not think that birth control pills are unequivocally a bad choice. She believes that women should absolutely be in charge of their own fertility. She simply thinks that women have not been given anywhere close to the full story.
Part of the problem is that the research is rather new, and much still requires exploration. However, what is unambiguously clear is that these pills influence women’s hormones, and women’s hormones influence nearly every single aspect of women’s physiology. To summarize (without explaining all the technical terminology behind these elaborate biological mechanisms), birth control pills, when taken on a daily basis, can change a woman’s personality, including the way she behaves, thinks and feels. The pill can decrease motivation and sex drive, dampen response to stress (including the good kind of stress that manifests itself as excitement and enthusiasm) and even affect romantic and marital partner choice. This, as Dr. Hill emphatically states, is huge.
One particularly disturbing finding is that birth control pills can instigate dysfunction of the HPA (hypothalamic-pituitary-adrenal) axis. Studies have shown that women on the pill have either a blunted cortisol response to stress, no cortisol response or even a decreased level of cortisol in response to stress (which is highly abnormal). In addition, daily cortisol rhythms, which help people wake up in the morning and make it through the day (hopefully with a bit of joie de vivre), become lower and flatter. Additional studies suggest that this flat-lining of the stress response (although overall cortisol levels remain high) can continue even after a woman stops taking the pill. It seems that pill-taking women are so overwhelmed with chronic high cortisol signaling that the HPA axis tries to shut down. This can lead to issues such as brain-volume loss, mental health disturbances (including major depression) and even immune system malfunction. Dr. Hill does not fully explore the link to autoimmunity in this book (nor does she address the pill’s effects on the gut microbiome), but she does note that 78 percent of people suffering from autoimmune diseases are women. It is not much of a stretch to see that the pills they commonly take on a daily basis could be contributing to the prevalence of autoimmunity.
More information is always a good thing, and any woman who is on birth control or considering starting a regimen would benefit from reading Dr. Hill’s well-researched book. While written in a warm and chatty style (Dr. Hill has no problem using humorously sarcastic footnotes, asterisk-filled expletives or multiple exclamation marks to make a point), she also includes the science behind the “why” of it all, along with illustrations and charts. A high schooler could easily read this book and probably should. I wish I could have read it all those years ago, instead of simply accepting what a man in a white coat said as the ultimate be-all and end-all.
Every substance that we put in our mouth can have an effect on our entire system, and therefore on our lives. In the age of information, women have been encouraged to take control of their reproductive health, their well-being and their future by accessing information like that contained in this book. Go forth, women of the world, and read. Two thumbs up.
This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly journal of the Weston A. Price Foundation, Fall 2020