Period Ah Period Eugh Period When?

by Enica King

This project talks about the menstrual cycle, tracking and cycle syncing. It deals with Unit 9: Reproductive System and the Learning Objective: Describe how ovulation, menses, pregnancy, and spermatogenesis are hormonally regulated.

The menstrual cycle (MC) is a roughly monthly feedback loop of hormonal nature (Gombert-Labedens et al., 2024) that involves the female reproductive system, nervous system and endocrine system. It is the process of maturing an ovum, and preparing the womb to grow an embryo in the event of successful fertilization, aided by timely hormonal stimulation by estrogen, follicle stimulating hormone (FSH), luteinizing hormone (LH) and progesterone, as graphed below.

Figure 1. Menstrual cycle and hormone graph (Clue)

Many young and middle-aged women to this day know about their MC only insofar as their monthly menstruation, failing to grasp the continuity of it over each month and how it impacts daily life; they don’t understand why they’re moody the week before their period, or have more appetite, or can lift heavier seemingly at random. Cycle syncing is a relatively new movement that calls for the alignment with one’s diet, exercise and workload with whichever of the four menstrual phases one finds herself in. For instance, estrogen has the function of stimulating the maturation of follicles, but budding research also highlights estrogen as an indicator for peak muscle strength within the MC (Kissow et al., 2022). Another example is eating iron-rich foods to account for blood loss during menstruation.

However, beyond quality of life, accurate tracking and monitoring of the MC is key to infertility, PMS, menopausal issues, and hormone-related diseases (Masuda et al., 2025). With the technological age came the possibility to advance such menstrual trackers with machine learning. Most readily available commercial trackers involve users logging their data onto apps, which a review led by Lynette Lyswinski in 2024 concluded was prone to errors and not effective. A much more precise but less common approach combines biometric signals and machine learning instead, measured using wearable devices. Basal body temperature (BBT) is one indicator of cycle stage since the skin temperature was found to be at its lowest in the follicular phase, rising to a maximum in the luteal phase and decreasing into the menstrual phase if no conception occurred, in which case it remained high  (Lyzwinski et al., 2024). The other main measurement is heart rate variability, which seems to follow a similar rise and fall as BBT. A study by Hazuki Masuda made the case for circadian heart rate and nadir, which is the minimum heart rate reached during deep sleep, producing much more precise algorithms than with BBT, but Lyswinski’s review points out that in reality, it depends more on the type of device worn (arm, ear or intravaginal) and consistency of use than which measure is prioritized. What the studies did agree on was mainly the need for further investigation into the effect of cycle syncing and possible improvements on the technology.

This STEAM project involved baking cookies to symbolize each stage of the MC, captured within the flavors and motifs, where the differences between each cookie symbolizes the ebb and flow of the MC. For menstruation, I made red velvet cookies, with rich, creamy, red motifs, to symbolize the shedding of the endometrium, blood, and reset of the cycle. The second follicular phase, in contrast, is characterized by happy, bright energy as the body prepares a follicle for ovulation and experiences a surge in LH and estrogen. It is captured in these brown sugar cookies with white chocolate chunks. Thirdly, ovulation comes as a cookie with honey drizzled over it, as FSH peaks and the body is ready for conception. Finally, the last phase is the luteal phase, and I chose dark chocolate chunk cookies with a hint of bitterness to encapsulate the negative emotions and mood swings of this time.

In essence, research into mechanisms of the MC and how to harness it using wearable devices is in full swing and can provide crucial insights into female health in all aspects of life. By understanding and properly tracking one of the female body’s core mechanisms I am hopeful we can ultimately lead happier, healthier, harmonious lives.

References

Clue. Inside the Brain Illustration. Clue, 27 Mar. 2024, https://helloclue.com/articles/menstrual-cycle/how-does-the-menstrual-cycle-reshape-your-brain. Accessed 9 Apr. 2025.

Gombert-Labedens, Marie, et al. “Using Wearable Skin Temperature Data to Advance Tracking and Characterization of the Menstrual Cycle in a Real-World Setting.” Journal of Biological Rhythms, vol. 39, no. 4, Aug. 2024, pp. 331–50. EBSCOhost, https://doi.org/10.1177/07487304241247893.

Kissow, Julie et al. “Effects of Follicular and Luteal Phase-Based Menstrual Cycle Resistance Training on Muscle Strength and Mass.” Sports medicine (Auckland, N.Z.) vol. 52,12 (2022): 2813-2819. doi:10.1007/s40279-022-01679-y 

Lyzwinski, Lynnette, et al. “Innovative Approaches to Menstruation and Fertility Tracking Using Wearable Reproductive Health Technology: Systematic Review.” Journal of Medical Internet Research, vol. 26, Jan. 2024, pp. 1–12. EBSCOhost, https://doi.org/10.2196/45139. 

Masuda, Hazuki, et al. “Machine Learning Model for Menstrual Cycle Phase Classification and Ovulation Day Detection Based on Sleeping Heart Rate under Free-Living Conditions.” Computers in Biology and Medicine, vol. 187, Mar. 2025, p. 109705. EBSCOhost, https://doi.org/10.1016/j.compbiomed.2025.109705. 

Appendix A. Working on the project