County Obstetrics & Gynecology

STL Leaders in Women’s Healthcare

Your Menstrual Cycle

A Comprehensive Guide to Each Phase

The menstrual cycle is the monthly series of hormone-driven events in the body that culminates in either a menstrual period or pregnancy.

Every month, you form a cyst on your ovary that normally can grow to 2.5-3.5 cm.

As this cyst grows through the month it produces a hormone called estrogen.

Rising estrogen has a major effect on the uterus:

It signals the uterine lining to regrow and thicken
Blood vessels increase, and the lining becomes healthier and more structured
The uterus is preparing to support a potential pregnancy

.. the cyst then ruptures which is called ovulation.

After ovulation, the follicle that released the egg transforms into the corpus luteum, which produces progesterone.

Progesterone causes the uterine lining to:

Become thicker and more nutrient-rich
Develop glands that secrete substances to nourish an early pregnancy
Shift from growth mode to support mode

If the egg is not fertilized, the corpus luteum breaks down, causing progesterone and estrogen levels to fall. Without these hormones, the uterine lining can no longer be maintained and begins to shed—leading to the next menstrual period and the start of a new cycle.

These predictable hormonal changes are what allow the uterus to cycle monthly between shedding, rebuilding, and preparing for pregnancy.

The Menstrual Cycle

Each menstrual cycle starts on the first day of a period (menstruation) and ends on the day before the next period.

The average menstrual cycle is:

28 days.

Normal Range:

21-35 days in an adult women

21-45 days in a teen when first starting your cycles

Normal length of the menstural flow:

3-7 days.

In the United States, 14% to 25% of women have irregular menstrual cycles.

Are you experiencing abnormal bleeding?

The menstrual cycle is divided into four phases:

Menstrual
Follicular
Ovulation
Luteal

Menstrual Phase: The Beginning of the Cycle

The menstrual cycle starts the first day of a period.

When a pregnancy doesn’t occur, levels of the hormones estrogen and progesterone drop, causing the lining of the uterus to shed. The average period lasts for three to five days, although a period lasting seven days isn’t unusual

During the menstrual phase you might experience symptoms like:

Bloating
Moodiness
Breast soreness
Fatigue

Follicular Phase

This phase starts simultaneously with the first day of the menstrual period and continues until ovulation. It lasts for about 14 days in total. During this phase, eggs mature in the ovary in preparation for ovulation and possible fertilization (pregnancy).

The hypothalamus in the brain releases gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to release follicle-stimulating hormone (FSH).

FSH causes the follicles — fluid-filled sacs in the ovaries that house the growing eggs — to develop.

One follicle and its egg will mature the fastest. That dominant follicle releases estrogen, which causes thickening of the uterus lining in preparation for a possible pregnancy.

Ovulation

This is the point in the cycle when the follicle releases a mature egg, thanks to a surge in LH.

Ovulation happens at around the middle of the cycle — day 14 of a 28-day cycle.

This is the time in the cycle when a pregnancy can occur.

How do I know when I am ovulating?

You might experience symptoms like:

Sore breasts
Mild cramps
Bloating
Increased sex drive
Mood swings
Changes in appetitie
Increase in vaginal discharge or slick and slippery mucus (like egg white).
Abdominal pain, often on one side of the tummy.

Luteal Phase

This phase lasts from day 15 to day 28 of the menstrual cycle.

The luteal phase is named after the corpus luteum, which forms in the ovary after an egg is released. This structure makes hormones—mainly progesterone and a small amount of estrogen—that help the lining of the uterus grow thicker and stronger. This prepares the uterus to support a pregnancy if the egg is fertilized.

The egg travels down the fallopian tube. If it meets with a sperm and conception (fertilization) occurs, the fertilized egg may implant in the uterus, resulting in pregnancy.

An egg can only survive for one to two days.

If the egg isn’t fertilized, the corpus luteum dissolves, hormone levels drop, and a menstrual period starts.

During the Luteal phase you might experience symptoms like:

Sore breasts
Bloating
Acne
Mood swings
Changes in appetitie
Trouble sleeping

Optimize Your Health for a Smoother Menstrual Cycle

The menstrual cycle is intimately associated with a woman’s physiologic balance, and there are many factors that can affect the menstrual cycle by disrupting this balance

Hormonal imbalances, stress, extreme exercise, sudden weight changes, certain medications, and reproductive health conditions like PCOS and endometriosis can all affect the regularity of the menstrual cycles.

Here are a few things you can do to restore the balance and reduce symptoms from various stages of the menstrual cycle.

Eat a Cycle-Friendly Diet

An overall well-balanced diet with an emphasis on whole foods is a good strategy. These are some foods to eat.

Omega-3 Fatty Acids Fatty fish like salmon, flax and chia seeds, nuts, soybean and canola oils, and fortified eggs, juices, and milk are rich in this nutrient. Omega-3s may make premenstrual syndrome (PMS) symptoms less severe.
Iron You’ll find this mineral in poultry, fish, oysters, eggs, beans, whole grains, and iron-fortified cereals. Extra iron in the diet will replenish what you lose while menstruating, especially if you get heavy periods. It also fights PMS-related fatigue.
Calcium Foods like low-fat milk and yogurt, as well as salmon, are rich in calcium. Calcium not only strengthens bones but is also helpful for combatting mood swings, cramps, and other menstrual symptoms.
Complex Carbohydrates The body burns whole grains like brown rice and oats, as well as legumes like beans and lentils, slowly. This keeps blood sugar levels steady and prevents hunger-related mood swings and food cravings.

Here are some things to avoid:

Salt Cut back on sodium-rich foods like lunch meat and processed foods. Too much salt can contribute to bloating, sore breasts, and swelling in the body.
Caffeine and Alcohol Drinking alcohol, soda, or coffee within a few hours of bedtime can disrupt sleep.

Stay Active

Energy levels rise and fall throughout the menstrual cycle. You might feel more energized right after a period, and more sluggish in the week before a period as hormone levels drop. Exercise can boost sagging energy levels, and it might make period cramps less severe.

Get Enough Sleep

Restful sleep is important to combat fatigue. Research also finds that good sleep helps improve mood during the menstrual cycle.

Many women have trouble sleeping, especially right before their period. To improve sleep, cut back on alcohol and caffeine, especially in the hours before bedtime.

Do something relaxing before bed, like reading or taking a warm bath.

Manage Stress

A body under stress produces excess cortisol, a hormone that can disrupt the normal release of estrogen and progesterone and upset menstrual cycle regularity.

Eating a well-balanced diet, exercising daily, and getting good quality sleep are ways to reduce stress. Also try calming techniques like meditation, deep breathing, and yoga.

To manage these symptoms:

Do moderate-intensity exercises like walking or yoga for 30 minutes a day.
Get at least eight hours of sleep each night; seven to nine hours are generally recommended for adults.
Eat a well-balanced diet with extra fruits, vegetables, lean proteins, and whole grains, and less sugar, alcohol, and caffeine.
Relieve stress with techniques like deep breathing, yoga, or meditation.
Don’t smoke, which can worsen period symptoms.

Medications and supplements that may help include:

Nonsteroidal anti-inflammatory drugs (NSAIDs) to relieve pain from cramps or breast tenderness
Antidepressants, anti-anxiety medications, and diuretics to relieve symptoms such as moodiness or bloating
Hormonal birth control to relieve symptoms
Some vitamins or supplements, such as curcumin, St. John’s wort, or evening primrose oil.