When it comes to understanding the female reproductive system, it can be difficult to grasp due to the lack of health education in schools and the scientific jargon associated with it. For those with uteri, you may have wondered quite often, what is happening to my body? Why is my period early, late, or, perhaps, not stopping at all? Why is it so painful? These irregularities and menstruation symptoms that you might have experienced can create a sense of disconnect with your body.
With the menstrual knowledge simplified here, we hope that it will empower and enable you to have greater control of your menstrual health, well-being, and sex life, if necessary.
The Menstrual Cycle Simplified
The purpose of your menstrual cycle is to prepare your body for pregnancy every month, and it’s a natural and beautiful process. This monthly cycle continues from your first period after you hit puberty (average age 13) until you reach menopause (average age 51).
Your menstrual cycle is controlled by the the hypothalamus and the pituitary gland in the brain, a series of hormones, and the uterus. These components communicate the rising and falling levels of hormones between one another to regulate your menstrual cycle.
To give you a memorable visual of the uterus, picture yourself holding a soccer ball under each armpits. The soccer ball represent your is ovary, the arms are your fallopian tubes, and the torso is your uterus body. You’re now a walking uterus! Haha, ok… bad joke. Moving on.
The menstrual cycle is averaged to 28 days and is divided into three phases. It is normal for the cycle to last between 21 and 35 days. The first day of your period (bleeding) is the beginning of your monthly menstrual cycle. The bleeding lasts about 3-5 days. Each month, one of the ovaries develops an egg and releases it. This is called ovulation. Then, the egg will travel down the fallopian tube to meet with a sperm to fertilize. If there is no fertilization, the egg will leave with your menstrual flow, which is triggered by the drop of hormone levels from your previous cycle.
Cycle Days Overview
|Cycle Days (Approximate)||Events||Causes||How you might feel|
||Normal physical menstruation symptoms:
*Symptoms can occur few days before menstruation (PMS – Premenstrual Syndrome)
|Days 6 – 14||
|Days 14 – 28||
||Premenstrual Syndrome (PMS) – Emotional symptoms:
Premenstrual Syndrome (PMS) – Physical symptoms:
Comprehensive explanation of the three menstrual phases:
1. Pre-Ovulatory or Follicular Phase (Days 1 – 14)
The follicular phase lasts from first day of the period until ovulation. While menstrual bleeding occurs, the ovary is working to prepare for ovulation. At this point in every cycle, the hypothalamus secretes gonadotropin releasing hormone (GnRH) which then causes the pituitary gland (located at the base of the brain) to release follicle stimulating hormone (FSH) and luteinizing hormone (LH). FSH and LH control the maturation of ovarian follicles in the ovary. Each ovarian follicle contains an egg (oocyte) and the follicles compete to grow the fastest during each menstrual cycle. Only one dominant follicle release an egg each cycle.
- As follicles grow → increase estrogen levels in blood → negative feedback to signal pituitary gland to secret less FSH.
- Less FSH means only enough for 1 follicle to win!
- Estrogen level is now high and steady → sends positive feedback to signal pituitary gland to secrete more FSH and LH to prepare the dominant ovarian follicle to rupture and release the egg. Think of it like saving a lot of energy 1-2 days before ovulation.
- Spike in estrogen also signals the endometrium to thicken (the layer that will shed) and make more vaginal mucosa to welcome the sperm.
- Increase of LH causes brief surge in testosterone → inducing sex drive at the most fertile time of the cycle on about day 12 – 14.
What causes period cramps and changes in bowel movement? A high level of prostaglandins hormone is produced when you are menstruating and this hormone contributes to menstrual cramps. Prostaglandins can also cause your bowel to contract creating bowel changes such as constipating or diarrhea.
2. Ovulatory Phase (Day 14)
The mature egg is now released (ovulated) due to the spike of FSH and LH. The egg will move to the fallopian tube where fertilization may take place if it meets a sperm. If there is no fertilization, the egg will disintegrate after about 24 hours.
3. Post-ovulatory or Luteal Phase (Days 15 – 28)
Right after the egg is released, the remains of the ovarian follicle turn into corpus luteum. Corpus luteum produces progesterone to prevent the endometrial lining from shedding. There has been robust evidence correlating progesterone as the driving factor for impairing emotional processes. This is better known as the emotional symptoms of PMS (Premenstrual Syndrome) or “Shark Week”.
Once the fertilization window begins to close after day 15, the corpus luteum disintegrates and is replaced by corpus albicans. Corpus albican doesn’t produce hormones; therefore, progesterone and estrogen level will be at their lowest. This signals the thickened endometrium to shed again – the beginning of a new menstrual cycle or in another words, another preparation for pregnancy.
- Low progesterone + low estrogen = a new menstrual cycle
Please note that as each woman’s menstrual cycle varies, the cycle days stated above are approximated according to a “normal cycle.” If you are experiencing menstrual cycle irregularities, abnormal bleeding, and abnormal symptoms of menstruation, please contact your healthcare provider for further investigations.