Progesterone 101

Progesterone 101

Dana Alloy Dana Alloy

The menstrual cycle is a valuable, yet understated, indication of a woman’s overall health. It is even considered to be a “vital sign” by the American College of Obstetrics and Gynaecology, meaning that it is of similar importance to heart rate, blood pressure, or temperature (1). Thus, just as checking one’s pulse is a useful metric, so is assessing the health of one’s menstrual cycle. There are two main events that can be assessed - menstruation and ovulation. While menstruation is the most pronounced aspect of the menstrual cycle to evaluate, ovulation is actually the most significant, as it catalyzes the process required to create progesterone (2). 

Ovulation & progesterone 

The menstrual cycle begins with the first day of menstruation (2). Following this, a follicle is stimulated, and an egg is developed. After about two weeks (though this varies by individual), the follicle ruptures, releasing the mature egg (ovum). Ovulation is signified by the release of the ovum, which makes a pregnancy possible. The ovum then travels from the ovary via the fallopian tubes and is available for the fertilization of sperm. 

However, an equally important aspect of ovulation is that it catalyzes a cascade of other hormonal changes. The most important of these hormonal shifts is the production of progesterone. Ovulation is the only way to generate a healthy level of progesterone. When the ovum is released during ovulation, the emptied follicle develops into a temporary endocrine structure called the corpus luteum (3). The corpus luteum produces progesterone for about two weeks, with levels peaking around day 21 of the cycle, though this can vary, depending on your cycle length (4). If no pregnancy occurs, the corpus luteum breaks down. Without the corpus luteum, progesterone levels decline, causing the endometrium to shed (2). The start of a new period marks the beginning of the next menstrual cycle, and the process begins again. The progesterone produced in this process is integral for both fertility and, more importantly, overall good health.

As the 'pro-gestation' hormone, progesterone prepares the body for a healthy pregnancy. 

Progesterone & pregnancy

As the 'pro-gestation' hormone, progesterone prepares the body for a healthy pregnancy. It maintains the endometrium and creates optimal conditions for the implementation of an embryo in the uterine wall (3). When planning a pregnancy, tracking progesterone is important for two reasons. First, raised progesterone levels indicate whether or not ovulation has occurred since ovulation is the only means to significantly increase progesterone.  If ovulation does not happen - meaning an egg is not developed and expelled - then the corpus luteum never forms to produce progesterone, and progesterone levels do not increase. Thus, detecting progesterone rise during the cycle is a great metric for family planning. Second, progesterone is crucial in its own right to sustain the implantation of the egg after fertilization and is a vital hormone throughout pregnancy (3).

Progesterone & overall health

However, progesterone has a much more significant impact than just its contributions to gestation. Progesterone travels through the bloodstream and influences many processes throughout the body. It has substantial long term effects such as protecting against endometrial cancer and heart disease and building and maintaining healthy bones (5-7). Moreover, progesterone also provides utility in women’s lives each and every cycle. It regulates metabolism, reduces inflammation, and is also beneficial for helping with sleep, keeping the nervous system calm, and soothing mood (8-10).  

The chemical mechanisms that create these changes are both complex and subtle. When progesterone production is optimal, its influence may go unnoticed, particularly for individuals who are just beginning their journey of radical self-knowledge. However, an absence of progesterone can be quite notable and certainly lead to a greater appreciation of the hormone.  When progesterone levels are too low, it can contribute to physical changes such as shorter menstrual cycles and premenstrual symptoms. Too little progesterone also creates an imbalance in brain chemistry and can lead to anxiety, insomnia, or even PMDD (11-13).

Low progesterone

Since progesterone balances out the effects of estrogen, too little progesterone can create relative estrogen dominance (14,15). This can lead to swollen breasts, water retention, or heavy periods, as well as increased risk for breast or endometrial cancer. Low progesterone levels are also associated with menstrual disorders such as PCOS, hypothalamic amenorrhea, and endometriosis (14,16,17). Knowing whether or not progesterone production is occurring is advantageous in understanding whether or not one may have a menstrual syndrome or disorder. 

Lastly, it is important to recognize that hormonal contraceptives provide progestin rather than progesterone, which is absorbed very differently in the body. If you are on a hormonal contraceptive that hinders ovulation, you do not receive any of the health benefits that progesterone provides (18-20).

Detecting progesterone 

As you can see, progesterone is one powerful hormone. Having healthy progesterone levels is, therefore, not only a key indicator but a crucial ingredient for a healthy body. Tracking progesterone is important for fertility, general well being, and assessing for menstrual disorders. Luckily, the consistent, cyclical changes throughout the menstrual cycle make it possible to keep a pulse on this hormone. By determining whether progesterone increases halfway through the cycle (after ovulation), one can obtain the best understanding of that cycle's health.

The inne minilab is the first technology sensitive enough to effectively detect progesterone via saliva in the comfort of one’s home. In utilizing this powerful tool, every individual can map their progesterone levels in the context of their own lives. By getting to know progesterone, you can understand where you stand in your cycle and your greater health experience.


1. The American College of Obstetrics and Gynecology, Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign, Obstetric Gynecology, 2015,  126(6) pp 143-6.

2. Reed, B.G. and Carr, B.R., The Normal Menstrual Cycle and the Control of Ovulation, 2018, Endotext, pp.1-32

3. Taraborrelli, S, Physiology, production and action of progesterone, AOGS, 2015, 94, pp. 8-16

4. Filicori, M. Butler, J.P., & Crowley, W.F., Neuroendocrine regulation of the corpus luteum in the human. Evidence for pulsatile progesterone secretion. The Journal of Clinical Investigation, 1984, 73(6), pp. 1638-1647

5. Prior, J.C., Progesterone within ovulatory menstrual cycles needed for cardiovascular protection: an evidence-based hypothesis, Journal of Restorative Medicine, 2014, 3(1), pp 85-103

6. Kim, J.J., and Davis, E.C., Role of Progesterone in Endometrial Cancer, Thieme Medical Publishers, 2010, 28(1), pp. 81-90

7. Prior, J.C., Progesterone as a Bone-Trophic Hormone, Endocrine Reviews, 1990, 11(2), pp. 386-298

8. Melcangi, R.C. et. al, Levels and actions of progesterone and its metabolites in the nervous system during physiological and pathological conditions, Progress in neurobiology, 2014, 113, pp. 56-69

9. Schussler, P. et. al, Progesterone reduces wakefulness in sleep EEG and has no effect on cognition in healthy postmenopausal women. Psychoneuroendocrionology, 2008, 33(8) pp. 1124-1131

10. Sayeed, I. and Stein, D.G., Progesterone as a neuroprotective factor in traumatic and ischemic brain injury, Progress in brain research, 2009, 175, pp. 219-37

11. Le Melledo, J.M. and Baker, G., Role of progesterone and other neuroactive steroids in anxiety disorders. Expert Review of Neurotherapeutics, 2004, 4(5), pp. 851-860

12. Backstrom, T., Andreen L., Bjorn I., Johansson, I.M., and Lofgren, M. The role of progesterone and GABA in PMS/PMDD. Premenstrual Syndromes, 2007, pp 129-132

13. Malvika, D. and Supriya, A., Premenstrual Dysphoric Disorder: A Review, Journal of Psychosexual Health, 2019, 1(1) pp. 32-36

14. Marquardt, R.M., Kim, T.H., Shin, J.H., and Jeong, J.W., Progesterone and estrogen signaling in the endometrium: what goes wrong in endometriosis? International Journal of Molecular Sciences, 2019, 20(15), pp. 3822

 15. University of Wisconsin-Madison Whole Health Library, Estrogen Dominance, 2020, (article consulted on July-10-2020)

16. Shufelt, C.L., Torbati, T., and Dutra, E. Hypothalamic amenorrhea and the long-term health consequences. Seminars in Reproductive Medicine, 2017, 35(3), pp. 256-262

17. Joseph-Horne, R. et. al, Luteal phase progesterone excretion in ovulatory women with polycystic ovaries. Human Reproduction. 2002, 17(6), pp. 1459-63

18. Gompel, A., Plu-Bureau, G., Progesterone and Synthetic Progestin Controversies. JAMA Oncology, 2015, 1(70), pp.987

19. Pluchino, N. et. al, Progesterone and progestins: effects on brain, allogrenanolone and β- endorphin. The Journal of Steroid Biochemistry and Molecular Biology, 2016, 102(1-5). Pp. 205-13.

20. Feretti, G., Felici, A., Cognetti, F., The protective side of progesterone. Breast Cancer Research, 2007, 9(6) pp.1

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