An Introduction to the Menstrual Cycle Phases
There are three basic phases of the menstrual cycle. They include:
- Follicular Phase
- Ovulatory Phase
- Luteal Phase
- Menstruation (if pregnancy doesn’t occur)
Keep on reading for more details about the menstrual cycle.
What is a Menstrual Cycle?
Menstruation refers to the shedding of the uterine lining (endometrium) which is usually followed by bleeding. This phenomenon basically occurs in monthly cycles, otherwise terms as menstrual cycles, throughout a woman’s reproductive, except during pregnancy.
Menstrual cycle is when the female reproductive system undergoes regular natural changes and is what makes pregnancy possible. The purpose of the cycle is to produce oocytes and prepare the uterus for pregnancy.
There are four menstrual cycle phases which we’ll get into. But, first a bit of basic information about PMS, how long a menstrual cycle is, and what you can expect during your period.
About 80% of women have reportedly experienced some symptoms during the first two weeks leading to menstruation. It’s commonly referred to as PMS, and happens because of fluctuating hormones.
These premenstrual symptoms include:
- Tender breasts
- Feeling tired
- Mood changes
These symptoms may interfere in the regular daily activities of women and qualify as premenstrual syndrome in about 20% to 30% women.
Is your PMS Really Severe?
Do you experience severe PMS? You may have what’s known as Premenstrual Dysphoric Disorder (PMDD). You can learn more about it here: PMDD Symptoms and Treatment Options.
Natural Treatment for PMS Symptoms
How Long is a Menstrual Cycle?
The menstrual cycle begins with bleeding on the first day, which can also be called day 1. A cycle ends just before the next menstrual period starts. Normally, menstrual cycles can last between 21 to 35 days.
Is your cycle shorter than 21 days, and it feels like you’re always on your period? Learn more here.
Irregular Menstrual Cycles
Menstrual cycles are irregular in 20% of women, meaning they can either be longer or shorter in duration than the regular ones.
Usually, in the years immediately after menstruation starts (menarche) and before menopause, menstrual cycles vary the most and intervals between periods are the longest. Irregular periods are mostly cause by fluctuating hormone levels.
Learn more about irregular periods here.
How Long Does Bleeding Last?
Menstrual bleeding may last between 3 to 7 days, 5 on average. Blood may range between 1/2 to 2 1/2 ounces. Depending on the type, a sanitary pad or tampon can hold up to an ounce of blood. Unlike regular blood loss from an injury, menstrual blood does not clot unless the bleeding is very heavy.
However, some people may experience very heavy bleeding. This is bleeding that can last longer than 7 days, or be so heavy as to require changing a tampon or pad every hour or two multiple times in a row.
On the other hand, there are some people who may experience very light bleeding. There are a number of reasons for this, and it’s usually not a good thing, particularly if you’d like to get pregnant.
What Regulates the Menstrual Cycle?
Hormones regulate the menstrual cycle. The pituitary gland produces both the luteinizing hormone and follicle-stimulating hormone, both of which help promote ovulation and as well as stimulate the ovaries to produce estrogen and progesterone.
Estrogen and progesterone help stimulate both the breasts and uterus in preparation for potential fertilization.
When you approach menopause, these hormones start to fluctuate, which usually results in irregular periods. The same thing can happen when you start puberty. It takes most people a year or two before their periods start to become more predictable.
Learn about the Menstrual Cycle Phases
4 Menstrual Cycle Phases
The menstrual cycle consists of three phases:
- Follicular (before release of the egg)
- Ovulation (egg release)
- Luteal (after egg release)
What are the menstrual cycle days? Keep on reading to find out!
Phase 1: Follicular Phase
This phase starts on the first day of menstrual bleeding. The main focus of this phase is the development of follicles in the ovaries.
Beginning of the Follicular Phase
At the start of this phase, the uterine lining (endometrium) is full of nutrients and fluids that are meant to nourish an embryo. If the egg has not been fertilized, it means the estrogen and progesterone levels are low. Due to this, the top layers of the endometrium are shed, which is what causes menstrual bleeding.
At this point, the pituitary gland slightly boosts the production of follicle-stimulating hormone. This is the hormone that stimulates the growth of 3 to 30 follicles. Each of these follicles contains an egg.
The End of the Follicular Phase
Later, when the levels of the follicle-stimulating hormone decreases, only one follicle out of the rest (called the dominant follicle) continues to grow. This follicle will eventually start producing estrogen that will also cause the other follicles to break down. The estrogen in the dominant follicle also starts preparing the uterus and then stimulates the luteinizing hormone surge.
How Long Does the Follicular Phase Last?
The follicular phase can last at an average of 13 or 14 days. Out of all three phases, this phase varies the most in length. Though it tends to shorten out when nearing menopause.
Then when the level of luteinizing hormone dramatically increases (surges), the phase comes to an end. This results in the release of the egg (ovulation) and transitions into the next phase.
Phase 2: Ovulatory Phase
The ovulation phase begins after the dramatic surge of luteinizing hormone levels. These hormones stimulate the dominant follicle to budge from the ovary’s surface, which finally ruptures, causing the egg to be released.
From here, there is a slight increase of the follicle-stimulating hormone. However, the function of the increase of follicle-stimulating hormone is not fully understood.
You may also notice a sharp increase in vaginal discharge. This is known as fertile mucus and it’s there to assist with getting pregnant.
How Long Does the Ovulatory Phase Last?
This phase can last from 16 to 32 hours. Then about 10 to 12 hours after the surge of luteinizing hormone levels, the phase ends when the egg is released. Upon its release, the egg can be fertilized for about 12 hours.
When the level of luteinizing hormone in the urine is measured, the surge can be detected. The purpose of this measurement is to determine when a woman is fertile. The chances of fertilization are greater when there is sperm in the reproductive tract before the egg is released. Most pregnancies happen when intercourse is practised three days before ovulation.
Is there Pain during the Ovulation Phase?
In some cases during ovulation, women experience a dull pain on one side of their lower abdomen, which is known as mittelschmerz (literally, middle pain). This pain may last from a couple of minutes to a couple of hours.
The pain is usually felt on the same side as the ovary that releases the egg, but its actual cause is not known. This pain may occur before or after the rupture of the follicle and may not happen in all cycles.
An egg that is released doesn’t alternate between both ovaries and seems to be random. For instance, if one ovary is removed, the other ovary releases an egg after every month.
Phases of the Menstrual Cycle
Phase 3: Luteal Phase
The luteal phase starts after ovulation and lasts about 14 days (unless fertilization occurs) and finishes off before a menstrual period. During this phase, the ruptured follicle shuts off after it releases the egg and then forms a structure known as corpus luteum that produces increasing amounts of progesterone.
The progesterone prepares the uterus if the embryo is planted. The progesterone then causes the endometrium to be filled with fluids and nutrients to nourish a possible embryo. Progesterone causes the mucus in this cervix to thicken so that bacteria and sperm do not enter the uterus.
This hormone can also cause a slight increase in body temperature during this phase and remain that way until menstruation occurs. The increase in temperature can be used to determine if ovulation has occurred.
The level of estrogen during this phase is high and it also stimulates the endometrium to thicken. The boost in estrogen and progesterone widens the milk duct in the breasts (dilate), causing them to swell and become tender.
That’s the luteal phase of the menstrual cycle!
Phase 4: Menstrual Phase
If the egg is fertilized during the luteal phase, no menstruation will occur. However, if the egg is not fertilized, then bleeding will occur. This means that your body is shedding the endometrial lining.
The first day of bleeding is considered to be the first day of the new cycle.
Menstrual Cycle Diagram
Check out this diagram to learn more about the Menstrual Cycle Phases:
Menstrual Cycle Phases and Hormones
The menstrual cycle is regulated by hormones. You might be curious as to how this works? Let’s take a look.
Week 1 (menstruation): At the beginning of your menstrual cycle, levels of progesterone and estrogen are low.
However, estrogen begins to rise steadily, and you may find your mood and energy levels increasing throughout the week.
Week 2 (after menstruation until ovulation): During this phase, estrogen levels steadily rise, until they peak at ovulation.
During the later part of this phase, testosterone rises slightly, which can lead to an increase in sexual desire.
Week 3 (the day after ovulation, lasting 8 days): During this part of the menstrual cycle, estrogen drops sharply, then rises slightly, and then drops again.
At the same time, progesterone is on the rise, which is often what causes PMS like symptoms.
Week 4 (last few days of the menstrual cycle before menstruation): During the last few days before your new cycle begins, both estrogen and progesterone drop sharply.
How Can I Track My Menstrual Cycle Phases?
It can be very helpful to keep track of your menstrual cycles for a number of different reasons:
- Your doctor may need this information
- You may be curious about it
- It can be useful if you’re trying to get pregnant
- If can be useful if you’re trying NOT to get pregnant, although we still recommend using condoms, birth control, an IUD or other form of contraception as the “natural” method has high failure rates
The basic way to track your menstrual cycle is to use something simple like your cellphone calendar. Write down:
- The first day of your period
- How long the bleeding lasted, and if it was a normal flow
- PMS symptoms
- Any spotting, or unusual symptoms throughout your cycle
You can learn more about tracking your menstrual cycle here.
Menstrual Cycle Phases: Your Thoughts?
Any questions or comments about the menstrual cycle phases? Leave a comment below and let us know.
Tammy Ford is the resident expert for all things Women’s Health (vaginal discharge and infections, perimenopause, menstrual cycles and more) and is also a chief tester of all things eco-friendly period products. She has a Master of Science in Nursing (MSN) and specializes in reproductive health.
You can contact her via email: [email protected]