What Happens During Your Menstrual Cycle?
Did you know that your menstrual cycle affects more than just your period? It can impact various aspects of your body, including your energy levels, mental health, libido, and skin.
The menstrual cycle is a complex process that involves hormones communicating with the brain and other organs. While its primary purpose is to achieve pregnancy, it affects different parts of your body in unique ways.
How Long Does the Menstrual Cycle Usually Last?
Menstrual cycles typically last around 28 days but range from 21 to 45 days. It's not uncommon for cycles to be irregular, especially during periods of mental or physical stress or significant weight fluctuations. If the body is not prepared for pregnancy, ovulation will not occur.
However, irregularities in menstrual cycles may indicate a more serious issue. If your cycle is shorter than 21 days, it could suggest an infection or changes in the cervix.
Additionally, ovarian cysts can disrupt hormonal balance, while conditions like PCOS can lengthen menstrual cycles to over 35 days.
As women age, irregular cycles can signify declining fertility and the start of perimenopause.
Which Hormones Regulate the Menstrual Cycle?
Oestrogen
Follicles in the ovaries produce oestrogen, which is a female sex hormone. Oestrogen is vital in regulating the menstrual cycle by thickening and making the uterus lining, known as the endometrium, more receptive to a fertilised egg. Oestrogen reaches its highest levels just before ovulation.
Progesterone
The corpus luteum, the remaining follicle after ovulation, produces progesterone, the other major female sex hormone. Its primary function is to maintain the endometrium and prepare it for implantation. It usually peaks around day 21 of the menstrual cycle, approximately one week after ovulation.
FSH
The pituitary gland in the brain produces follicle-stimulating hormone (FSH), which stimulates the maturation of egg follicles. FSH also plays a crucial role in initiating puberty.
During menstruation, FSH levels increase. However, FSH levels decrease a few days before ovulation as the body selects only one egg for further development. FSH levels then rise again, helping to facilitate ovulation, before decreasing to their lowest levels just before menstruation.
LH
The brain produces luteinising hormone (LH), which triggers ovulation and releases the most mature egg. LH production is stimulated by a peak in oestrogen levels, and the surge of LH leads to ovulation.
The Key Phases of the Menstrual Cycle Explained
1. Follicular Phase
When?
This phase occurs from approximately the onset of your menstrual period until ovulation.
What Occurs?
Your ovaries contain eggs that are continually attempting to grow, but they are only released for potential fertilisation when the hormonal conditions are just right. During this phase, the pituitary gland responds to low levels of estrogen and progesterone by producing FSH (follicle-stimulating hormone). FSH promotes the growth of follicles and the production of estrogen. The uterine lining thickens in preparation for a potential fertilised egg to implant, and FSH levels decrease when estrogen levels reach a specific point.
How Might You Feel?
- You might experience migraines, particularly if you are prone to hormonal migraines, because estrogen levels are low at the start of the follicular phase.
- Increased libido may be noticed as estrogen tends to boost sex drive during this phase, as it's your body's way of trying to facilitate pregnancy. This is also why you may feel fullness in your vagina and notice more slippery discharge.
- Your breasts can also feel fuller towards the end of the follicular phase.
2. Ovulation
When?
Ovulation typically occurs around the 14th day of a 28-day menstrual cycle.
What Occurs?
Towards the end of the follicular phase, one mature egg (or occasionally, one from each ovary) emerges as the winner of the growth competition and is prepared for release.
This mature egg generates a substantial amount of estrogen, which signals the pituitary gland to release LH (luteinising hormone). LH facilitates the release of the egg. Once released, it takes approximately 24 hours for the egg to traverse the fallopian tube, where fertilisation must occur for a potential pregnancy. The egg remains viable for 24 hours, while sperm can survive up to 5 days.
How Might You Feel?
- You may experience an increase in body temperature, usually around half a degree Celsius, immediately after ovulation, as it's conducive to sperm survival.
- Your cervix may become softer and more open. As blood flow to the uterus peaks, the cervix opens to welcome sperm. During this time, you may notice that it feels soft and open, and you might observe an egg white-like discharge that supports sperm mobility.
3. Luteal Phase
When?
The luteal phase of the menstrual cycle commences after the egg's release during ovulation, approximately 14 days before the onset of your period.
What Occurs?
After ovulation, the egg leaves behind the corpus luteum, which begins producing progesterone to facilitate the maturation of the uterine lining.
The body anticipates the descent of a fertilised egg through the fallopian tube and its growth to a size suitable for attachment to the uterine wall, which takes several days. Around day 21, the corpus luteum becomes less effective, leading to a decline in progesterone production. When progesterone and estrogen levels drop significantly, the uterine lining breaks down, resulting in menstrual bleeding.
How Might You Feel?
- Premenstrual Syndrome (PMS): If you're part of the 80% of women who experience some form of PMS, this phase is when you'll likely encounter it. With lower progesterone levels, you might feel agitated, irritable, and low during this stage.
- Hormonal Acne: Hormonal acne tends to be more pronounced during the luteal phase, primarily due to reduced progesterone levels.
4. Menstruation
When?
The onset of your menstrual period is designated as day 1 of your menstrual cycle, concurrently marking the commencement of your follicular phase, as explained in phase 1 above. The average menstrual cycle spans 28 days, although this duration can vary among individuals.
What Occurs?
Menstruation ensues if pregnancy doesn't occur as the uterine lining breaks down. During the subsequent luteal phase, characterised by elevated progesterone levels, the production of FSH (follicle-stimulating hormone) and LH (luteinising hormone) by the brain decreases to a minimum.
Once progesterone levels drop again, the cycle resets, returning to the follicular phase.
How Might You Feel?
- Menstrual Bleeding: Most individuals experience a menstrual period lasting 3-5 days, although this duration can vary.
- Potential Cramping: Mild cramping and discomfort are common during menstruation. If you experience severe pain, heavy bleeding, or concerning symptoms, it's advisable to consult a doctor, as there may be an underlying issue.
Menstrual Cycle Phases and Hormonal Changes
The table below summarises the main phases of the menstrual cycle, their duration, hormonal activity, and common physical or emotional changes you may experience.
| Phase | Approx. Duration | Key Hormones | What Happens | How You Might Feel |
|---|---|---|---|---|
| Follicular Phase | Days 1–14 | FSH, Oestrogen | Egg development and uterine lining thickening | Energised, improved mood |
| Ovulation | Around Day 14 | LH, Oestrogen | Egg release and peak fertility | Increased libido, slight temperature rise |
| Luteal Phase | Days 15–28 | Progesterone | The uterus prepares for a possible pregnancy | PMS symptoms, fatigue |
| Menstruation | Days 1–5 | Hormones drop | Shedding of the uterine lining | Cramps, low energy |
When Are You Most Fertile During the Menstrual Cycle?
When ovulating, which typically occurs 14 days before the start of your period, it can be beneficial to become familiar with your body's menstrual cycle. Doctors recommend paying attention to your vaginal discharge, checking your cervix, and being aware of any breast tenderness. These observations will help you recognise patterns and signals in your body.
How the Menstrual Cycle Changes Through Different Life Stages
From The Onset Of Your Initial Menstruation.
The typical age at which girls experience their first period is slightly above 12 years, but this can range from 9 to 15 years. It takes some time for your body to adapt and regulate the balance of hormones, but after a year, your menstrual cycles should become more predictable.
Throughout Different Life Stages, Including the Possibility of Pregnancy
Except for pregnancy, breastfeeding, and occasional missed periods due to high stress levels, your menstruation should remain regular until you reach your mid-40s.
As we age, the quality of our eggs decreases, leading to a heightened risk of miscarriages and chromosomal abnormalities. The corpus luteum, responsible for producing progesterone, becomes less efficient, potentially resulting in shorter menstrual cycles. This change is typically the earliest indication of entering perimenopause.
Concluding With Perimenopause And Menopause
Over time, the supply of eggs diminishes, causing your menstrual cycles to become less frequent. Despite not ovulating, your ovaries will continue to produce estrogen, which prompts the lining of your uterus to thicken. However, since there's no ovulation, progesterone production decreases, and eventually, this built-up lining is shed.
This is why you might experience irregular but heavy and prolonged bleeding until you're around 51. After this period, if you haven't had a period for a year, you're officially in menopause.
Mobi Doctor can provide valuable assistance by offering convenient online consultations with experienced doctors. With Mobi Doctor, you can easily access medical expertise and seek professional guidance from home, ensuring prompt and accessible healthcare solutions.
