Hello everyone! My name is Klara Jandusikova, I am currently in my third year at Colby College where I am majoring in Psychology with a concentration in Neuroscience. I also have two minors: Sociology and Human Development. One cool fact about me is that I am from the Czech Republic but have been studying in the USA for the past five years. My freshman year, I took Biological Basis of Behavior and was intrigued by all the topics we discussed. One topic that particularly spiked my interest was the sex differences unit where we discussed gonadal hormones and their different function in males and females as well as among animals.

To further explore my interest in sex differences and gonadal hormones specifically, I decided to do an independent study for which I read the book This Is Your Brain on Birth Control: The Surprising Science of Women, Hormones, and the Law of Unintended Consequences, by Dr. Sarah E. Hill. This book reveals crucial information on how birth control (the pill) affects women and their surroundings which is what every woman taking the pill should know. There are three sections in the book. The first is about what it means to be a woman from a biological perspective. The second one discusses how the pill works and how it affects women’s lives and brains. The third section covers some larger issues with the pill (Hill, 2019). Given this, I decided to divide the book into 3 units. I will write a blog post about some intriguing facts or findings from each section as I read. So far, I have read the first section.

While I was reading, I generated four different types of questions: reactionary, clarifying, imaginative, and reflective questions. These questions serve as a guide for future research on topics of interest as well as gaps in my knowledge or in the existing literature. In terms of the clarifying questions and with me still being new to this neuroscientific topic about hormones, I did some additional research on both estrogen and progesterone to better understand their function in female bodies which will then allow me to better comprehend the effects of the pill. In fact, Singh and others (2008) wrote an article discussing what animal models can teach us about estrogen and progesterone. Specifically, they argued that results from these animal studies are consistent and therefore may have predicted the results from Women’s Health Initiative (WHI). Furthermore, there are a few factors that influence estrogen or progesterone-induced neuroprotection which include the age or the specific subtype of the steroid hormone. These animal studies illustrate that the neuroprotective effects of estradiol are influenced by (reproductive) age which is probably not very surprising to many of you. Although animal models do not cover everything, they are a useful tool for the development of future hormone-based therapies for women across their lifetimes.

With a deeper understanding of the functions of estrogen and progesterone in female bodies, I was very surprised and excited when I learned that the fact that women feel differently across the menstrual cycle is supported by research findings. Something I found fascinating is that female body scents differ across the cycle in a way that women at high fertility smell sexier to men compared to women at low fertility (Gildersleeve et al., 2012; Havlicek et al., 2006). This is mainly determined by the different ratios of estrogen and progesterone levels during the cycle.

Women’s hormonal changes across the two parts of the menstrual cycle. Taken from This Is Your Brain on Birth Control

To further explore this notion, Gildersleeve and colleagues (2012) examined how men perceive women’s scent at their high versus low fertility days. All the women tested had a regular menstrual cycle and did not use any form of hormonal contraception prior to the study. The women wore cotton pads on both underarms for a day on high and low fertility days to collect their scents. Then, men rated the samples for preferences and attractiveness of the scents. The results suggested that men rated high fertility scents samples as more attractive as well as pleasant, and sexy. This makes sense because the bodies of females at a high fertility rate are prepared to conceive a baby and therefore attracting men is necessary in order to do so.

However, this is not observed in women using the pill because they lack estrogen surge (Kuukasjarvi, 2004). A study conducted by Kuukasjarvi and others (2004) examined whether ovulation is concealed or can be determined using scents. Both men and women rated the attractiveness of T-shirts worn by women who either used the pill or did not. The results demonstrated opposite effects of pill users and nonusers which may further suggest that the pill flattens the attractiveness of female odors. So, does this mean that using the pill makes women less attractive or sexy? I am not sure, but I am hopeful that I will further my knowledge in the next section of the book “This Is Your Brain on Drugs” and will report back to you in a week!

References

Gildersleeve, K. A., Haselton, M. G., Larson, C. M., & Pillsworth, E. G. (2012). Body odor attractiveness as a cue of impending ovulation in women: Evidence from a study using hormone-confirmed ovulation. Hormones and Behavior, 61(2), 157–166. https://doi.org/10.1016/j.yhbeh.2011.11.005

Havlicek, J., Dvorakova, R., Bartos, L., & Flegr, J. (2006). Non-Advertized does not Mean Concealed: Body Odour Changes across the Human Menstrual Cycle. Ethology, 112(1), 81–90. https://doi.org/10.1111/j.1439-0310.2006.01125.x

Hill, S.E. (2019). This Is Your Brain on Birth Control: The Surprising Science of Women, Hormones, and the Law of Unintended Consequences. PenguinRandomHouse.com

Kuukasjarvi, S. (2004). Attractiveness of women’s body odors over the menstrual cycle: The role of oral contraceptives and receiver sex. Behavioral Ecology, 15(4), 579–584. https://doi.org/10.1093/beheco/arh050

Singh, M. (2008). Estrogens and progesterone as neuroprotectants: What animal models teach us. Frontiers in Bioscience, 13(13), 1083. https://doi.org/10.2741/2746