It’s empowering to learn about how your body functions…

I have spent a lot of time learning about the complex hormonal shifts that govern the menstrual cycle. My initial learning was through first hand experience, but it really wasn’t until much later that I learned what was occurring on a physiological level. I think it is empowering to learn more about how your body functions for a few reasons. First, you are better able to advocate for your health care needs when you become very aware of what is happening within your body; you are the expert on your body! Second, there is still a fair amount of shame about menstruation even though it is a natural process that occurs in a large portion of the global population. Talking about menstruation, and learning more about it are ways to move past shame. So, in this article I want to discuss the three phases of the menstrual cycle and the hormones that govern them.  

What does a typical menstrual cycle look like?

Before getting into those details, I want to discuss what a typical menstrual cycle looks like. Menstrual cycles can vary in length, but are typically 25-36 days long, with bleeding lasting from 3-7 days. Day one is the first day of bleeding, and to determine cycle length, just count until the next day one of bleeding. There can be more variability in cycle length in the years immediately following the first menstrual period (menarche) and immediately preceding menopause. If cycle length becomes irregular (https://juniperfamilyhealth.com/blog/2019/12/1/getting-to-know-your-menstrual-cycle-infrequent-or-absent-cycles-dr-chelsea-cole-nd), make sure to check in with your health care provider. Many people experience premenstrual syndrome (PMS) beginning a few days prior to bleeding, and the symptoms can vary from cramps to mood changes. While PMS is very common, that doesn’t mean you have to suffer each month, so make sure to speak to your health care provider if PMS is bothersome. People who menstruate are well aware of what menstruation feels like in their body, and can likely predict when it will occur. However, being a health care provider means that I talk a lot about menstruation, and have come to realize that not everyone knows about the inner details or recognizes when to see a health care provider. So, let’s get to know the phases and hormones of the menstrual cycle!

Follicular phase

The first day of the menstrual cycle is the first day of bleeding, which signals the beginning of the follicular phase. This phase lasts about fourteen days, and ends when ovulation (the release of an egg) occurs. Early in this phase, estrogen and progesterone levels are low, thereby causing the shedding of the endometrial lining (menstruation). Estrogen and progesterone are both released by the ovaries. Low levels of these hormones indicate to the brain to start releasing follicle stimulating hormone (FSH), which signals the ovaries to begin developing follicles. Follicles are small structures within the ovary that contain an egg. One follicle will continue to develop, produce estrogen, and will eventually release the mature egg. At this point, FSH levels decline.  

Ovulation

Around day fourteen, which is about halfway through a twenty-eight day menstrual cycle, luteinizing hormone (LH) will increase while FSH decreases. LH is another hormone released by the brain. This is known as the LH surge, which stimulates the release of an egg (ovulation). Estrogen levels begin to decrease, and progesterone levels begin to rise. The ovulatory phase lasts from sixteen to thirty-two hours, and ends once the egg has been released. The egg is usually released between ten and twelve hours after the LH surge. It is important to note that the egg can only be fertilized for about twelve hours after the release. In addition, measuring LH levels in the urine is one way to monitor for the fertile window, so that people can plan when to have intercourse if they are trying to become pregnant.

Ovulation can be associated with one-sided lower abdominal pain in some people. This is known as mittleschmerz, and can last a few minutes to a few hours. The pain usually occurs in the ovary that releases the egg, and may not occur with every cycle.

Luteal phase  

The second half of the cycle is the luteal phase, and it ends once bleeding begins. It typically lasts about fourteen days, and PMS will occur towards the end of this phase. LH and FSH levels decrease, and the follicle that released the egg becomes the corpus luteum, which produces progesterone. Progesterone levels rise, and both estrogen and progesterone play a role in developing the uterine lining (endometrium) in preparation for fertilization. Progesterone raises body temperature about 0.5C during this phase, so tracking the changes in body temperature throughout the menstrual cycle is another way to monitor whether ovulation has occurred. (https://juniperfamilyhealth.com/blog/2019/6/25/the-hot-amp-cold-of-fertility-basal-body-temperature-by-dr-meghan-van-drimmelen)

If fertilization does not occur, the corpus luteum breaks down, and no longer produces progesterone. Estrogen and progesterone levels decrease, and the uterine lining is broken down and shed out of the body, resulting in menstruation and the beginning of the follicular phase.

If an embryo (sperm and egg) is implanted in the uterus (pregnancy), the hormone, human chorionic gonadotropin (HCG), is produced which helps to maintain the corpus luteum, thereby maintaining high progesterone levels until the fetus can produce its own hormones. HCG is what is measured in the urine and/or blood to determine whether pregnancy has occurred.

My goal in sharing this information is to make you more familiar with your menstrual cycle, and I hope this article provides the foundational knowledge needed to understand menstruation.

To book an appointment with a Naturopath at Juniper Family Health, please contact the clinic at 778-265-8340 or info@juniperfamilyhealth.com or click here to book online.

References

Knudtson J. et al. (2019) Female reproductive endocrinology. Merck Manual. Retrieved from https://www.merckmanuals.com/en-ca/professional/gynecology-and-obstetrics/female-reproductive-endocrinology/female-reproductive-endocrinology - v1061582

Healthwise (2018) Normal menstrual cycle. HealthLink BC. Retreived from https://www.healthlinkbc.ca/health-topics/tn9930#tn9931