6 things you need to know about the menstrual cycle

Trying to conceive and the menstrual cycle 

The menstrual cycle is the engine for fertility and for all the ways we, as Reproductive Endocrinology & Infertility Specialists, Dr. Garcia and Dr. Wais at Markham Fertility Centre, can help someone get pregnant! We think about the menstrual cycle a million times a day and once someone understands the cycle – fertility and fertility treatments make SO much more sense. 

In this article, we will cover: 

  1. What is the menstrual cycle?
  2. What is menopause? What is perimenopause?
  3. The normal menstrual cycle
  4. The menstrual cycle hormones
  5. Key definitions
  6. The follicular phase, ovulation, and the luteal phase  

What is the menstrual cycle?

The menstrual cycle refers to the choreographed dance of hormones coming from the brain, affecting the ovary and the downstream effects of those hormones on the uterine lining, egg maturation, and potential pregnancy.

Menarche refers to the first menstrual period a person with a uterus will have.

Here are a few quick facts related to menarche: 

  • The average age of menarche in Canada is about 12.7 years old according to the Canadian Pediatric Society
    • The age is getting earlier throughout the years. 20-30 years ago the average age was 13 and 100 years ago the average age was 13.5
    • The most commonly cited cause for this trend is higher body fat percentage in young people with ovaries due to our modern diets 
    • The average woman in Canada will have about 465 periods in her life!

What is menopause? And perimenopause? 

Menopause refers to having no periods for 1 year. This is a challenging definition because you can only make the diagnosis 1 year after it happens, which is not helpful. 

Related to menopause, we need to talk about perimenopause – an ill-defined time leading up to menopause that can range from 4-8 years. The first symptom of perimenopause is irregular periods. 

  • The average age of menopause in Canada is 51
    • The best predictor of when you will go through menopause is when your mother or relatives with ovaries went through menopause 

The normal menstrual cycle

It is so important to know what is normal! 

According to the Society of Obstetricians and Gynecologists of Canada,  a normal menstrual cycle:

  • Lasts between 24-38 days
  • Bleeding lasts 3-8 days
  • Blood loss 20-85 cc/cycle

Women with a normal volume of menstrual blood loss tend to:

  • Change pads/tampons at ≥ 3-hour intervals 
  • Use fewer than 21 pads/tampons per cycle – will vary depending on how often someone chooses to change 
  • Seldom need to change the pad/tampon during the night
  • Have blood clots less than 1 inch in diameter
  • Not be anemic

The menstrual cycle and hormones

First, let’s introduce the main hormones involved and next we’ll see how they work together.

Estrogen – a hormone produced by the ovaries as the eggs in the ovaries mature. It causes the lining of the uterus to thicken.

FSH and LH – follicle stimulating hormone and luteinizing hormone – hormones produced by the pituitary gland in the brain that act on the ovary. 

Progesterone -a hormone made by the ovaries after ovulation. It dominates the second half of the menstrual cycle. In pregnancy, progesterone levels are even higher and the placenta takes over the production of this crucial hormone.

Key definitions 

Menstruation AKA the period

The cycle begins with menstruation (day 1 by convention is the first day of full flow), commonly known as the period. This phase lasts about 3-8 days, during which the body sheds the uterine lining that built up in the previous cycle. Menstruation is a normal and healthy process, and the amount and duration can vary among individuals.

Follicular phase

The follicular phase begins with menstruation. This phase can last about 7-21 days and involves the development of follicles in the ovaries, each containing an immature egg. As these follicles grow, they produce estrogen, which stimulates the thickening of the uterine lining in preparation for a potential pregnancy.

Ovulation

Ovulation is a crucial moment in the menstrual cycle, typically occurring around the middle of the cycle, approximately 14 days before the start of the next menstruation. During ovulation, a mature egg is released from one of the follicles and begins its journey down the fallopian tube, making it available for fertilization by sperm. This phase is kick-started by a surge in luteinizing hormone (LH) triggered by rising estrogen levels.

Luteal phase

After ovulation, the luteal phase begins and lasts around 14 days. The ruptured follicle transforms into a structure called the corpus luteum, which produces progesterone. Progesterone helps maintain the uterine lining in case a fertilized egg is in the uterus, preparing the body for pregnancy. If fertilization does not occur, the corpus luteum breaks down, leading to a decrease in estrogen and progesterone levels and the onset of menstruation.

Often we talk about the menstrual cycles as having two phases.

The first half of the cycle or follicular phase, is characterized by the growth of the follicle in preparation for ovulation. During this time, estrogen is the predominant hormone. 

The second half of the cycle occurs after ovulation and is called the luteal phase. During this time, progesterone is the predominant hormone. 

It is important to mention that if a woman is on the birth control pill, using hormonal IUDs, depo-provera, or any other type of hormonal birth control, it will affect the cycle so everything we’ve said so far may not apply! 

When it comes to symptoms, it is important to note that every person’s experience of their menstrual cycle is different and it can vary month-to-month! That means that you may not notice any of the symptoms below and they will vary cycle to cycle. 

Symptoms of the Follicular Phase

Increased Energy Levels: Rising estrogen levels can contribute to a boost in energy and a general sense of well-being.

Improved Mood: Many individuals report a more positive mood and increased motivation during the follicular phase.

Enhanced Libido: Higher estrogen levels often correlate with an increase in libido, contributing to a higher level of interest in sexual activity.

Reduced Bloating: As menstruation concludes, water retention decreases, leading to reduced bloating and a lighter feeling.

Improved Concentration: Some people find that cognitive functions, including concentration and mental clarity, improve during the follicular phase.

Lower Stress Levels: The initial days of the follicular phase may lead to a decrease in stress and anxiety levels compared to the premenstrual phase.

Exercise Performance: Increased energy levels and improved mood can contribute to enhanced exercise performance during this phase.

Skin Radiance: Some individuals notice an improvement in skin appearance, including a natural glow and reduced acne, as estrogen supports skin health.

Thicker Hair: Estrogen influences hair growth and texture, and some may experience thicker and shinier hair during the follicular phase.

Optimism and Sociability: Higher estrogen levels are associated with increased sociability and a generally more optimistic outlook on life.

Lubrication and Vaginal Comfort: Estrogen contributes to increased vaginal lubrication, which can enhance comfort during sexual activity.

Symptoms of Ovulation 

Mild Pelvic Pain (Mittelschmerz): Some people experience a brief, mild pain or cramping on one side or both sides of the lower abdomen, indicating the release of the egg. This is known as Mittelschmerz.

Changes in Cervical Mucus: The consistency and colour of cervical mucus may change during ovulation. It often becomes clear, slippery, and more stretchy, resembling egg whites. This type of mucus facilitates sperm movement.

Increased Libido: Hormonal changes, particularly a surge in estrogen, can lead to an increase in libido or sexual desire during ovulation.

Breast Tenderness: Some individuals may experience mild breast tenderness or sensitivity due to hormonal fluctuations during ovulation.

Abdominal Bloating: Hormonal changes can cause water retention, leading to a feeling of abdominal bloating.

Heightened Senses: Some people report increased sensitivity to taste, smell, or touch during ovulation, potentially related to hormonal changes.

Slight Increase in Basal Body Temperature (BBT): Tracking basal body temperature can reveal a slight increase after ovulation due to the influence of progesterone.

Mood Changes: Hormonal fluctuations during ovulation may affect mood, leading to increased feelings of positivity or heightened emotional sensitivity.

Spotting: Some individuals may experience light spotting during ovulation, which is usually attributed to hormonal changes affecting the uterine lining.

Symptoms of the Luteal Phase

Breast Tenderness: Increased levels of progesterone can cause breast tissue to become more sensitive and swollen.

Bloating: Hormonal fluctuations may lead to water retention, resulting in a feeling of bloating or mild weight gain.

Mood Swings: Changes in estrogen and progesterone levels can affect neurotransmitters in the brain, leading to mood swings, irritability, or heightened emotional sensitivity.

Fatigue: The body’s metabolic rate may slightly increase during the luteal phase, potentially causing feelings of fatigue or tiredness.

Cramping: Some individuals may experience mild abdominal cramping or discomfort during the luteal phase, which can be associated with changes in the uterine lining.

Acne and Skin Changes: Hormonal fluctuations may influence oil production in the skin, leading to acne breakouts or changes in complexion.

Headaches: Hormonal changes can trigger headaches or migraines in some individuals during the luteal phase.

Food Cravings: Changes in hormones may lead to an increased appetite or specific cravings, especially for carbohydrate-rich or comfort foods.

Sleep Disturbances: Some individuals may experience changes in sleep patterns, such as difficulty falling asleep or staying asleep, during the luteal phase.

Increased Sensitivity: Heightened sensitivity to external stimuli, such as light, sound, or smell, can occur during this phase.

The menstrual cycle is a fascinating orchestra of many hormones that have effects all over the body! When trying to conceive or when undergoing fertility treatments, a knowledge of the menstrual is key to understanding what’s going on. Tracking your own menstrual cycle is a powerful tool that can help you with fertility but also to understand your body and things you may be experiencing.  

References 

Canadian Paediatric Society. (2006). Menstruation in girls and adolescents: Using the menstrual cycle as a vital sign. Paediatrics & Child Health, 11(9), 579–583.

Society of Obstetricians and Gynaecologists of Canada. (2013). Abnormal Uterine Bleeding in Pre-menopausal Women. Journal of Obstetrics and Gynaecology Canada, 35(5) S1-S28.