In her 2019 book, This Is Your Brain on Birth Control: How the Pill Changes Everything, researcher Sarah Hill describes the wide-ranging effects of birth control pills on a woman’s brain and hormonal health. Dr. Hill earned her PhD in evolutionary psychology from UT Austin and, despite focusing her research on the effect of women’s hormones on behavior, she recounts that she never realized the impact of the birth control pill on the brain and behavior until more than a year after she stopped taking the pill herself. Initially, she chalked up the changes she personally experienced after discontinuing the pill as being “all in her head,” but a few chance conversations with colleagues at psychology conferences motivated her to dig a little deeper. Ultimately, her search led to this book detailing the effects of the birth control pill on the female brain. It is written for a popular audience, primarily women of reproductive age who either take birth control pills or may consider them as an option.
Dr. Hill introduces her book by declaring that her goal is to put the reader in a “position of power.” She states repeatedly that her aim is not to discourage or dissuade women from using the pill, but rather provide them with information about the wide-ranging effects of the pill on the brain, equipping them to make a more fully informed decision about the best form of family planning for them. Despite her desire to educate women to make more informed family choices, she never introduces natural or fertility awareness-based methods (FABMs) as an option for pregnancy prevention. This is an unfortunate oversight, as these are the only methods of family planning with no medical side effects and effectiveness rates comparable to, or better than, the pill.[1]
In the first part of the book, Dr. Hill gives an overview of a woman’s biology. She rightly refers to the female cycle as the “ovulatory cycle”—not the “menstrual cycle” —since ovulation is the main event.[2] Dr. Hill then describes the intricate orchestration of hormonal changes during the various phases of the cycle, showing how they affect women’s sexual desire, mate preference, and more. She makes the important point that the sex hormones, estradiol and progesterone, have the most powerful influence on the woman’s brain. These hormones impact how women think, feel, and behave, depending on where a woman is in her cycle.
“You are a different person on the birth control pill than you are when you’re off the pill.”
In part two—“This is Your Brain on Drugs”—the author describes in greater detail how the pill “fundamentally changes a woman’s hormonal profile” in its aim to prevent ovulation (and pregnancy). Although accurate, this is an oversimplification that fails to consider the additional mechanisms of action of hormonal contraception with implications for fully informed consent.[3] However, after this simplified discussion on how the pill affects ovulation, the author does a good job describing the different types of birth control pills and their various side effects depending on the synthetic progestins that are used. As a physician, I found the discussion fascinating and the accompanying table detailing how the different progestins are derived and what various side effects they have very informative.
The breadth and magnitude of the potential adverse impact of the pill becomes clear as Dr. Hill highlights the different parts of the brain and body affected. Areas of the brain responsible for learning, memory, attention, emotional processing, language processing, social interaction, self- control, and eating behaviors may all be impacted. Within the body, the pill may impact the stress response, gut hormones, and the immune system, which may impact a woman’s ability to eventually conceive and maintain a pregnancy. To illustrate the potentially harmful, wide-ranging impact of the pill, Dr. Hill likened its use to prevent ovulation as “sort of like dropping an atomic bomb on your house to blow out a candle. Dropping a bomb on a house will blow out a candle. It’s just that its effects are … sufficiently …non-specific.”
Overall, Dr. Hill does a decent job describing research highlighting the adverse impact of the pill on attraction, sexual satisfaction, stress, and depression. One large population-based study conducted in Denmark and published in JAMA Psychiatry demonstrated that women who used non-oral hormonal birth control (i.e., the birth control patch or ring or levonorgestrel IUD) had a 40-90% higher risk of depression as compared to naturally cycling women.[5] In adolescents, the risk was two to three times higher.
In the final section of her book—“The Big Picture”—Dr. Hill discusses the societal effects of the pill, including the implications for the workplace, as well as marriage and pregnancy. She praises the pill’s promise of pregnancy-free sex, claiming it motivated more women to pursue education in the early 1970s. Yet, in terms of the “mating market” and marriage, she admits the devastating impact of the pill, which has made it more difficult for women interested in relationships to find a comparable partner. As for motherhood, long-term pill use brings with it an increase in infertility as more women delay pregnancy until an age when it becomes more difficult to have children naturally. Caught between the “pros” and the “cons,” she can only then conclude in a letter to her daughter—and to us—that the pill is a “big deal” and that she—we—should be fully informed before deciding to use it. “You are a different person on the birth control pill than you are when you’re off the pill.”
As a successful female researcher steeped in progressive academic culture, Dr. Hill is careful not to demonize birth control. She only wants to put women in a “position of power” in order to be able to give “informed consent” by explaining its potential impacts on a woman’s brain and behavior. She shows the many negative effects of the pill based on a critical review of the literature, but these important considerations are often followed by sweeping generalizations about positive aspects of the pill. For example, she credits the pill’s success in preventing pregnancy as the primary reason more women went to college. However, there are two issues with this hypothesis. First, the pill, like every other form of birth control, does not make the odds of an unplanned pregnancy effectively zero, as the author repeatedly claims throughout the book. Rather, the unintended pregnancy rates with typical use of the pill range from 6–9%.[4]
Second, the advent of the pill cannot be considered the sole reason for an increase in women’s college attendance. In the United States, the women’s rights movement, economic imperatives, and equal opportunity legislation to prevent employers from only considering men for positions all played a role.
Overall, Dr. Hill’s willingness to research and write boldly about such a “political hot potato” is admirable. She offers much-needed straight talk. However, given her interest in providing women with research so that they can make informed decisions regarding family planning, she leaves out one of the most empowering family planning methods of our time: charting the signs or biomarkers of the female cycle using a natural or fertility awareness-based method of family planning (NFP/FABM).[5] Since charting these biomarkers reflect the hormonal changes women experience on a cyclical basis, this can truly empower women and help them effectively achieve or avoid pregnancy without the widespread effects of the pill on individual women, couples, families, and even society as a whole.
[1] M. D. Michael, M. Duane, A. Lind, I. Sinai and J. Golden-Tevald, “Fertility Awareness-Based Methods of Family Planning: A Review of Effectiveness for Avoiding Pregnancy Using SORT,” Osteopathic Family Physician
5, no.1 (2013): 2–8. Also, M. Duane, J. B. Stanford, C. A. Porucznik and P. Vigil, “Fertility Awareness-Based Methods for Women’s Health and Family Planning,” Front. Med. 9 (2022).
[2] P. Vigil, C. Lyon, B. Flores, H. Rioseco, and F. Serran, “Ovulation, A Sign of Health,” Linacre Quarterly 84, no. 4 (2017): 343–55.
[3] W. L. Larimore and J.B., “Postfertilization Effects of Oral Contraceptives and Their Relationship to Informed Consent,” Arch Fam Med 9, no. 2 (2000):126–33.
[4] C.W. Skovlund, L. S. Mørch, L. V. Kessing and Ø. Lidegaard, “Association of Hormonal Contraception with Depression,” JAMA Psychiatry 73, no. 11 (2016): 1154–62. Also, A. Sundaram, B. Vaughan, K. Kost et al., “Contraceptive Failure in the United States: Estimates from the 2006–2010 National Survey of Family Growth,” Perspect Sex Reprod Health 49, no. 1 (2017): 7–16. Also, J. Trussell, “Contraceptive Failure in the United States,” Contraception 83, no. 5 (2011): 397–404.
[5] M. D. Michael, M. Duane et al., “Fertility Awareness-Based Methods of Family Planning,” and M. Duane, J. B. Stanford et al., “Fertility Awareness-Based Methods for Women’s Health and Family Planning.”
