What to Know About Your Menstrual Cycle

In Pelvic Health by Rachel DaofLeave a Comment

By: Rachel Daof

Here at PHRC we see conditions that affect that dreaded time of the month: our periods. As we have written before, conditions like endometriosis can directly affect menstruation. Other menstrual related issues include period cramps, nausea, bowel movement issues, headaches, and many other symptoms all driven by our cycle. To many of us, these are things we merely deal with on a monthly basis, but we have to start thinking about why our menstrual cycle is important. In fact, our cycle is so important that the American College of Obstetricians and Gynecologists (ACOG) are calling it the fifth vital sign.1 In this blog I’ll help you sort out what your body is doing during the cycle and what to expect in each phase.

So what is the menstrual cycle? The menstrual cycle is the monthly series of changes a woman’s body goes through in preparation for the possibility of pregnancy.2 Your cycle length is when you start bleeding for one cycle to the onset of bleeding of the next.3 You may have heard the average length of a cycle is 28 days; however, most cycle lengths range between 25-30 days. In this article, I’ll break down your menses in four phases: menstrual, follicular, ovulation, and luteal. Here’s what happens in each phase:

Menstrual Phase: (four to six day average)3

Your cycle starts the first day you start your period. This phase starts if you had not gotten pregnant, and you shed your uterine lining. Uterine lining sheds because progesterone levels are low at this time which decreases the blood flow to your superficial endometrial layers. The endometrium releases prostaglandins that contract the uterus to physically shed these layers. What was once at its lowest point, estrogen starts to become produced by growing follicles which stimulate regeneration of the endometrial epithelium at around day two of your cycle.

  •     Average menstrual blood loss: 30mL
  •     Abnormal amount of blood loss: >80mL

 Some conditions that cause heavy menstrual bleeding4:

  •     Hormone imbalance like PCOS
  •     Uterine fibroids
    • Here is a link to 5 KCRW’s Bodies podcast for an anecdotal story about uterine fibroids.
  •     Polyps
  •     Adenomyosis

Menstrual cramps during this phase is a common symptom, and some of you have heard that magnesium can help mitigate these symptoms. This podcast10 by Natural MD radio talks about the science behind how this works.

Follicular Phase: (3,6)

The variability in women’s cycle lengths are usually because this phase’s length across all women can differ and range between 10-16 days. The follicular phase starts at the same time the menstrual phase starts, and it ends when you ovulate. At this time, your ovarian follicles develop coining it the follicular phase. Here, you release follicle stimulating hormone (FSH) which stimulates the ovaries to produce 5-20 small sacs (i.e. follicles) each containing an immature egg. Between days five and seven of your cycle your body selects a single follicle out of the group to mature. By day eight, that follicle exerts its dominance and grows and suppresses the growth of other follicles which resorb. As we are in the heat of the follicular phase, estradiol levels rise leading to a cascade of events that produce a secretion of progesterone. The estrogen thickens the lining of the uterus to prepare for an embryo if you do get pregnant.

Ovulation Phase: 3,6

This is the precious time during your cycle that you may want to pay attention to if you’re trying (or not trying) to get pregnant. During this time your body is beaming with estrogen, triggering a cascade of events to release luteinizing hormone (LH). The predictor of ovulation is the peak of LH surge caused by the massive production of estradiol at this time. Ovulation occurs 34-36 hours after the peak of LH. This is when your ovary releases a mature egg and finds its home in the uterus waiting for sperm to fertilize it. If sperm does not find its way to the egg, the egg dies or dissolves.

During this phase, you may notice that your cervical fluid/discharge is a lot stickier, and it should be like raw egg whites. The consistency and contents of this discharge help protect the sperm making it easier to get pregnant.7

Luteal Phase: 3,6, 8,9

This phase is usually 14 days long, which is relatively consistent for all women. During this time, after the follicle releases the egg, it turns into what’s called the corpus luteum. The corpus luteum secretes progesterone and primes the endometrium to implant a fertilized ovum. However, if you don’t get pregnant, it resorbs, and after resorption, estrogen and progesterone levels rapidly drop. Then you re-enter the menstruation phase. PMS can be present in this time due to hormone changes.

The above shows what happens during a normal cycle. However, here at PHRC we see patients that deviate from the norm (e.g. those with endometriosis, adenomyosis, PCOS, etc). Remember, your cycle is now considered a fifth vital sign. If you suspect your body is not doing the above, please have it checked out by a qualified provider. On another note, with some of these conditions come pelvic pain which lead to subsequent muscle guarding perpetuating pelvic pain. Here at PHRC, we are able to identify and treat musculoskeletal dysfunctions that may accompany the above conditions.



  1. Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign. ACOG. https://www.acog.org/Clinical-Guidance-and-Publications/Committee-Opinions/Committee-on-Adolescent-Health-Care/Menstruation-in-Girls-and-Adolescents-Using-the-Menstrual-Cycle-as-a-Vital-Sign. December 2015. June 12, 2019.
  2. Menstrual Cycle: What’s Normal, What’s Not. Mayoclinic. https://www.mayoclinic.org/healthy-lifestyle/womens-health/in-depth/menstrual-cycle/art-20047186. May 11, 2016. June 12, 2019.
  3. Reed B. Carr B, The Normal Menstrual Cycle and Control of Ovulation. Endotext. Aug 5, 2018; June 12, 2019.
  4. Menorrhagia. Mayoclinic. https://www.mayoclinic.org/diseases-conditions/menorrhagia/symptoms-causes/syc-20352829. July 15, 2017. June 12, 2019.
  5. https://www.bodiespodcast.com/resource-pages/2018/8/28/episode-2-bleeding
  6. Stages of Menstrual Cycle. Healthline. https://www.healthline.com/health/womens-health/stages-of-menstrual-cycle#ovulation. August 17, 2018. June 12, 2019.
  7. Guide to Cervical Mucus. Healthline. https://www.healthline.com/health/womens-health/cervical-mucus. December 11. 2017. June 12, 2019.
  8. The Menstrual Cycle. Sex Infor Online UCSB. http://www.soc.ucsb.edu/sexinfo/article/menstrual-cycle. May 29, 2018. June 12, 2019.
  9. Premenstrual Syndrome (PMS). OBGYNs of Canada. https://www.yourperiod.ca/abnormal-pain-and-menstrual-bleeding/premenstrual-syndrome-pms/
  10. Natural MD Radio: Magnesium for Women. Aviva Rom. MD. https://avivaromm.com/magnesium-for-women/

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