At GHT, we believe that the process and health of the female menstrual cycle is not taught thoroughly enough to the general population. The truth is, most people are aware of the vaginal bleed aka the “period” that occurs during a menstrual cycle, but many are unaware that a female’s period is only a small piece of the puzzle. The entire menstrual cycle is a symphony of fluctuating hormones that aim to support fertility, create an environment for potential pregnancy, as well as support multiple aspects of our overall health. It is a huge part of life as it happens on a monthly basis (unless actively pregnant or breastfeeding) and is often a constant for 30+ years of your life. We deeply believe that understanding your cycle can help empower you to take control of your health and wellness.
Hormones and organs involved in the menstrual cycle
We know that estrogen and progesterone are the dominating hormones for females and although they have leading roles in our cycles, there are some much needed supporting acts as well. Before we get too far in, let’s walk through the importance of estrogen and progesterone.
Estrogen is mainly responsible for the physical changes that occur during development: the growth of breasts and pubic hair, as well as the initiation of the menstrual cycle. Estrogen is mostly made in the ovaries, although the adrenal glands can produce it as well (particularly during menopause when the ovaries stop making estrogen). Estrogen impacts almost every tissue in the body as there are receptors throughout the brain, bone, skin, and heart.
Progesterone counters the effects of estrogen. Known as the “calming and feel good” hormone, it reduces anxiety, builds and maintains bone, promotes appetite, supports fat storage, supports blood vessel relaxation, impacts muscle contraction, and regulates nerve function amongst other roles. Progesterone is involved in preparing the endometrium (lining of the uterus) for the potential of pregnancy after ovulation. Progesterone is truly the yin to estrogen’s yang. It’s imperative for female health; which is why ovulation is a crucial occurrence, as you’ll see in a bit.
What other hormones are involved in the menstrual cycle?
Follicle Stimulating Hormone (FSH)- Stimulates the development of follicles (the house of the immature egg)
Luteinizing Hormone (LH)- Stimulates ovulation
Gonadotropin releasing hormone (GnRH)- hormone responsible for the release of follicle-stimulating hormone and luteinizing hormone from the anterior pituitary
Testosterone- Increases muscle and bone mass, drives libido, and supports the growth of body hair- ladies, this is required for health hormone balance
The Main Organs involved in the menstrual cycle:
Hypothalamus
Anterior pituitary
Ovary
Phases of the Menstrual Cycle
The menstrual cycle is the entirety of your cycle- meaning, from the first day of bleeding to the next first day of bleeding is 1 cycle.
The period is the alloted time where vaginal bleeding occurs (typically lasting 3-7 days).
The first day of bleeding (your period) is also the start of a new menstrual cycle.
Follicular (generally days 1-14)
The follicular phase usually lasts a total of about 14 days (or until ovulation). In the first 3-7 days, there is vaginal bleeding, or your period. The main purpose of this phase is to release follicle stimulating hormone (FSH) which will stimulate the ovaries to form a follicle for ovulation, in hopes of facilitating fertilization and pregnancy.
Let’s do a little anatomy and physiology review:
Low estrogen and progesterone signal a region in the brain called the hypothalamus to release gonadotropin hormone-releasing hormone (GnRH)
GnRH tells the pituitary gland to secrete FSH and start cranking out luteinizing hormone (LH)
FSH communicates with the ovaries to recruit a handful (3-30, each containing a single egg) of ovarian follicles to fight for the golden spot to be chosen
As you finish your period (usually between days 5-7), one egg gets chosen to fully mature
Though only one makes the cut, the maturing follicles still produce estradiol (contributing to the increased estrogen levels toward the end of the follicular phase)
LH stimulates ovulation & and increases estrogen levels
The increased estrogen levels initiate thickening of the endometrium (to get the body ready for the potential fertilization of an egg, resulting in pregnancy). Remember that in the absence of pregnancy, this thickened endometrium will be shed when the period comes again
This creates a positive feedback loop to continue the elevated concentration of GnRH, LH, and FSH
During the follicular phase, hormonal fluctuations are designed to support the body in preparing a home for the follicle that will be released and hopefully fertilized (during ovulation) to best support a healthy pregnancy. Typically, testosterone also rises in the latter half of the follicular phase. This increases libido, and is a good sign that ovulation is coming. The body is trying to get you in the mood to get pregnant.
Ovulation (lasts around 12-24 hours)
Ovulation is the report card of your menstrual cycle. Ovulation is the transition period that marks the end of the follicular and beginning of the luteal phases. Ovulation is when the mature follicle releases an egg. After the lucky follicle is chosen at the end of the follicular phase, a single egg is released, moved through the ovaries, down the fallopian tubes, and into the uterus for possible fertilization and implantation. Ovulation is also the main way you make progesterone.
The egg has 24 hours to be fertilized after being released. This is why keeping track of ovulation is important for fertility planning or avoiding pregnancy- talk about a crucial window.
Once in the uterus, the remainder of the follicle becomes a temporary endocrine gland called the corpus luteum. Fun fact: The corpus luteum has the highest blood supply per unit tissue of any organ in the body
This is how and when progesterone is released. The goal is now to maintain the thickening of your uterine lining in hopes of egg fertilization. Due to the increased progesterone levels, a few changes occur here, including a change in cervical mucus and an increase in basal body temperature.
If the egg is fertilized, pregnancy occurs.
If the egg isn’t fertilized, the corpus luteum begins to disintegrate, progesterone plummets, and the body starts to prepare for a new menstrual cycle.
Ovulation is absolutely necessary for a true period. If there is a bleed in the absence of ovulation, it’s likely an anovulatory cycle. This means there is so no advantageous fluctuation of estrogen and progesterone levels. Remember that the importance of the fluctuating levels of progesterone and estrogen exceed the period and menstrual cycle as they have an impact on overall health and wellness as well.
Luteal Phase (generally day 15-28, or until the next first day of the period)
The luteal phase is basically the time that the body is either preparing your body for pregnancy or putting the systems back in place to get back to baseline. If there was no fertilization, the corpus luteum turns into the corpus albicans as it disintegrates, which ultimately restores the menstrual cycle. The result is shedding of the endometrium, and thus day one of a new cycle.
Anatomy and physiology lesson, part 2:
GnRH is continuing to stimulate LH and FSH
LH stimulates the remaining part of the follicle to form the corpus luteum and stimulate the formation of estrogen and progesterone
The corpus luteum makes progesterone and estrogen
Progesterone maintains thickening of the endometrium, and inhibits uterine contractions. It also creates a - feedback loop on GnRH, LH, and FSH
Estrogen helps with the - feedback loop, disintegrating the corpus luteum and restoring the menstrual cycle
The end of the luteal phase now transitions to the first day of your period and a new cycle of your menstrual cycle as the result of no pregnancy
This is a simplified visual of how the hormonal symphony takes place, and how each small change impacts the rest of the body.
What should a period look like?
Disclaimer: everyone will have a experience
Period length- Typically 3-5 days, generally no more than 7
Type of blood - Should have the consistency of high quality maple syrup (flow easily) without any clots or clumps (jelly/ jam looking)
Color- It should be a bright red, which is indicative of a normal, healthy flow
Black, pink, purple, orange, or gray can be indicative of hormonal discrepancies, ovarian insufficiency, PCOS, or bacterial vaginosis.
Cramping- none to light cramping is normal
Clots- clots larger than the size of a raisin may be indicative of hormonal imbalance or nutrient deficiencies
How to know if you’re ovulating
Disclaimer: everyone has a different experience
There used to be the assumption that ovulation only happened on day 14 of a menstrual cycle, but we now understand that’s not always the case. Though that is theoretically optimal, the averages for most people can be found inside or outside that day 14 range.
Review: ovulation is the release of the egg from your ovary. It’s triggered by a surge in LH that stimulates the egg to be escorted to wait for fertilization. If none occurs, it will break down.
Your body sends subtle signs that you’re ovulating, you just have to listen.
Basal body temperature (BBT). This is a charting method to monitor daily temperature changes throughout your cycle. The rise in progesterone following ovulation triggers an elevation in your baseline temperature following ovulation until you get your period again.
Positive LH test. Since the surge in LH is responsible for ovulation occurrence, testing LH can help predict ovulation. LH strips test your urine for the presence of this hormone. It is recommended to start testing after your last day of bleeding until you get a positive test, in which you can expect ovulation to occur within the next 2-3 days.
Cervical mucus. Your vaginal discharge changes throughout your cycle. It’s an important mechanism to support the potential of fertilization. As you get closer to ovulation, the cervical mucus can resemble an egg white texture. This is due to the fact that it changes texture to help sperm survive and climb through to your uterus. Cervical mucus in absence of ovulation is usually creamy, sticky, or watery.
Increased sex drive. The body is quite literally trying to get ready for a baby. Well, we’ve all had the birds and the bees talk- you can’t make a baby without it.
Changes in cervix position. The cervix is at the very end of the uterus, connecting to the vagina. Depending on what phase of your cycle you’re in, the cervix can be in a different position and have a different touch. It’s typically higher, and slightly more open than usual before ovulation. Otherwise it closes and feels lower and firmer.
Signs you’re not ovulating:
Check out this blog on how to check your ovulation.
No LH surge
No spike in BBT
Irregular cycles (refer to “What should a period look like” section)
Amenorrhea or missing period
The menstrual cycle is so much more than a monthly bleed. It has an influence on multiple hormones and multiple organs, all working harmoniously to support your overall health and well-being. The body is an absolute masterpiece and works very hard to keep everything balanced. Tracking ovulation, cycle length, and symptoms associated with your entire menstrual cycle can be a great way to better understand your body and support it accordingly.
Katie Morra MS, RD, LDN, IFMCP is an Institute for Functional Medicine Certified Practitioner and Registered Dietitian Nutritionist specializing in gut and hormone optimization. Katie runs a fully virtual functional medicine practice, Gut Honest Truth, based out of Maryland. Katie focuses on the root causes of inflammation, autoimmune disease, irritable bowel syndrome, food sensitivities, hypothyroidism, hormone imbalance, adrenal dysfunction as well as other chronic disease states.
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