Menstrual Cycle Phases Explained: What Happens in Your Body Each Month

By the IDCC Health editorial team

The Menstrual Cycle at a Glance: Four Phases in One Month

Your menstrual cycle is the monthly series of changes your body goes through to prepare for a possible pregnancy. The average cycle lasts about 28 days, but anywhere from 21 to 35 days is considered normal for adults. Hormones rise and fall in a predictable pattern, and understanding that pattern helps you notice when something feels off. The cycle has four phases: menstrual, follicular, ovulation, and luteal. If you have questions about your own cycle, the team at our Gynecology practice in Brooklyn can help you sort out what is typical and what might need a closer look.

Many people feel physical and emotional shifts during the cycle, such as cramps, bloating, breast tenderness, or mood changes. These are common, but severe pain, very heavy bleeding, or cycles that are suddenly irregular may be signs of a female hormone imbalance or another condition. If you are unsure, a visit with a family medicine provider like Stella Geller DO can be a good first step, and our Primary Care services are available at locations including 445 Kings Highway. For more on what your symptoms might mean, see our guide on female hormone imbalance symptoms and causes.

• Menstrual phase: days 1-5, uterine lining sheds
• Follicular phase: days 1-13, follicles mature and estrogen rises
• Ovulation: around day 14, egg is released
• Luteal phase: days 15-28, progesterone peaks and uterus prepares

Phase by Phase: Menstrual, Follicular, Ovulation, and Luteal

The cycle is counted from the first day of one period to the first day of the next. Each phase is driven by changes in hormones, including estrogen, progesterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). These hormones tell the ovaries and uterus what to do each month. ACOG and MedlinePlus offer detailed guides on women's health and cycle basics.

The menstrual phase starts on day one. The lining of the uterus sheds, causing bleeding. This phase often lasts 3 to 7 days, with low estrogen and progesterone. The follicular phase overlaps with the end of the menstrual phase and lasts until ovulation. FSH helps a follicle, or fluid-filled sac, grow in the ovary. As it grows, it makes more estrogen, thickening the uterine lining. Mild cramps and bloating are common. If pain is severe or bleeding is very heavy, talk to a gynecologist. Our Gynecology team in Brooklyn can help you figure out what is normal for your body.

Ovulation usually happens around day 14 in a 28-day cycle. A sharp rise in LH triggers the ovary to release an egg. The egg travels down the fallopian tube. Some people feel a brief twinge on one side; others notice more discharge. After ovulation, the luteal phase begins. The empty follicle becomes the corpus luteum, which makes progesterone. Progesterone keeps the uterine lining ready for a possible pregnancy. If pregnancy does not happen, hormone levels drop and the cycle starts again. In the luteal phase, many people feel breast tenderness, mood changes, or fatigue, often called PMS. When symptoms are strong, they can be linked to a female hormone imbalance. For more on that, see our guide to female hormone imbalance symptoms and causes. If cycle changes affect your daily life, a primary care provider such as Stella Geller DO can review your overall health and refer you to the right specialist.

• Menstrual phase: days 1 to 5 or 7, uterine lining sheds, estrogen and progesterone are low.
• Follicular phase: days 1 to 13, FSH helps an egg follicle grow, estrogen rises and rebuilds the uterine lining.
• Ovulation: around day 14, an LH surge releases an egg from the ovary.
• Luteal phase: days 15 to 28, progesterone rises to support the uterine lining, then drops if pregnancy does not occur.

The Hormones Behind Each Phase: Estrogen, Progesterone, FSH, and LH

Four main hormones run the menstrual cycle: estrogen, progesterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). FSH and LH come from the pituitary gland in the brain; they tell the ovaries when to grow an egg and when to release it. Estrogen and progesterone come from the ovaries; they build up the uterine lining and then help shed it if pregnancy does not happen. Think of these hormones as a relay team, each passing the baton at the right time.

During the follicular phase, FSH rises and prompts a follicle to mature. That follicle makes estrogen, which thickens the uterine lining and triggers the LH surge that causes ovulation. After the egg is released, the empty follicle becomes the corpus luteum and produces progesterone, which keeps the lining stable. If no pregnancy occurs, progesterone and estrogen drop, and the lining sheds. These rises and falls explain common symptoms like cramps, bloating, breast tenderness, and mood changes. When hormone levels get out of balance, you may notice irregular periods, heavier bleeding, or worse premenstrual symptoms. For a closer look at those warning signs, see our guide to female hormone imbalance symptoms and causes.

If your cycle feels unpredictable or symptoms interfere with daily life, talk to a gynecologist. A family medicine doctor like Stella Geller DO can also help sort out whether your symptoms point to a hormone imbalance or another condition. Many women start with a primary care visit for blood work and a basic check, then get referred to gynecology if needed. You can schedule at our 445 Kings Highway office or another Brooklyn location. Regular check-ins with a gynecologist help you understand what is normal for your body.

• FSH: stimulates follicles in the ovary to grow during the follicular phase.
• Estrogen: thickens the uterine lining and triggers the LH surge before ovulation.
• LH: surges to release the mature egg during ovulation.
• Progesterone: stabilizes the uterine lining in the luteal phase and drops before menstruation.

Common Symptoms by Phase: Cramps, Bloating, Breast Tenderness, and Mood Changes

Each phase brings its own physical changes, and many are normal. The menstrual phase, days 1 to 5, is when the uterus sheds its lining. Cramps are common because the uterus contracts to push out the lining. Mild to moderate cramps that ease with rest or a heating pad are typical. If cramps are severe enough to miss work or school, talk to a gynecologist. For everyday questions about cycle symptoms, the Gynecology team at IDCC Health can help you figure out what is normal for your body.

During the follicular phase, which overlaps with the menstrual phase and continues until ovulation, estrogen rises. Many people feel more energy and fewer symptoms. Ovulation usually happens around day 14. Some notice a brief, one-sided twinge in the lower belly, which is usually harmless. After ovulation, the luteal phase begins. Progesterone rises, and bloating, breast tenderness, and mood changes often show up. These are sometimes called premenstrual syndrome, or PMS. ACOG notes that mild cramping and breast tenderness are common, and MedlinePlus lists mood changes as a typical premenstrual symptom.

Mood changes in the luteal phase are linked to shifting hormone levels, but they should not take over your life. If you feel anxious, depressed, or irritable for most of the month, or if physical symptoms like bloating and breast pain make daily activities hard, seek care. A family medicine provider such as Stella Geller DO can look at your overall health and help you decide what to do next. For a deeper look at how hormones affect the body, see our guide to Female Hormone Imbalance Symptoms and Causes. And if you are unsure whether to keep a gynecology appointment while on your period, our article Is It Okay to Have Medical Exam Even With Period? covers what to expect. You can schedule at our 445 Kings Highway office in Brooklyn.

• Menstrual phase (days 1-5): cramps, low back ache, fatigue
• Follicular phase (days 1-13): usually few symptoms, rising energy
• Ovulation (around day 14): brief one-sided pelvic twinge, light spotting in some cases
• Luteal phase (days 15-28): bloating, breast tenderness, mood changes, food cravings

Normal Variations vs. Signs That Warrant a Gynecologist Visit

Many menstrual symptoms that feel uncomfortable are actually normal. Mild cramps, bloating, breast tenderness, and slight mood changes can happen as hormone levels rise and fall. ACOG notes that periods can vary from person to person and month to month. What matters most is your own pattern. Knowing what is typical for you makes it easier to spot changes that deserve attention.

These changes can sometimes point to a female hormone imbalance. Our guide to Female Hormone Imbalance Symptoms and Causes explains more. MedlinePlus also offers reliable information about menstrual cycle problems. You do not need to wait until symptoms become severe. A gynecologist can help you sort out what is normal and what may need treatment. For routine concerns, a family medicine doctor such as Stella Geller DO can also provide care and refer you to a specialist if needed. Our Gynecology team sees patients at our Brooklyn offices, including 445 Kings Highway.

• Periods that last longer than seven days
• Bleeding so heavy that you soak through a pad or tampon every hour for several hours
• Bleeding between periods
• Severe pelvic pain
• Cycles that are consistently shorter than 21 days or longer than 35 days
• Sudden missed periods when you are not pregnant

How Cycle Changes Connect to Hormone Imbalance and Other Conditions

Cycle changes are often the first sign of a hormone imbalance. When estrogen and progesterone levels stay too high or too low, periods can become irregular, heavier, or more painful. Conditions such as polycystic ovary syndrome (PCOS), thyroid disorders, and perimenopause can all show up this way. For a plain-language overview, see our guide to female hormone imbalance symptoms and causes.

Because hormones affect many systems, cycle changes can also connect to other health issues. Heavy bleeding over time can lead to anemia, causing fatigue and shortness of breath. Severe pelvic pain might be linked to endometriosis or fibroids. If you notice lasting changes, start with a primary care visit. Stella Geller DO, a family medicine doctor, can review your history and order initial blood work. From there, a gynecologist can do a deeper evaluation.

Keep a simple record of your cycle length, flow, and pain level for at least two to three months. This helps your care team spot patterns. See a gynecologist if your periods come fewer than 21 days or more than 35 days apart, if you soak through a pad or tampon every hour, or if pain keeps you from normal activities. These can be signs of a hormone imbalance or another condition that needs treatment.

Getting Care in Brooklyn: Gynecologists, Primary Care, and Support

If you live in Brooklyn and have questions about your cycle, you do not need to figure it out alone. Gynecologists and primary care doctors often work together. Dr. Stella Geller DO, a family medicine physician, can provide routine care, order blood work, and refer you to a Gynecology specialist when needed. Our gynecology team at IDCC Health offers exams, testing, and treatment for many cycle-related concerns, from heavy bleeding to missed periods.

You can book visits at our Brooklyn offices, including 445 Kings Highway. During your appointment, your doctor may ask you to describe your cycle, track symptoms, and share any changes. ACOG notes that understanding your own pattern is one of the best ways to know what is normal. If your symptoms point to a hormone imbalance, your doctor may suggest blood work and a follow-up plan. For more on this, see our guide to Female Hormone Imbalance Symptoms and Causes. Your Primary Care doctor can also help with overall health, including thyroid, blood pressure, and other conditions that can affect your cycle.

Support does not stop at the exam room. If you have pelvic pain, our Pain Management and Physical Therapy teams can help. If you feel anxious or depressed around your period, Psychiatry services are available too. Our Rehabilitation and Occupational Therapy teams can also help with recovery and daily function. For questions about STD testing during a gynecology visit, see our article on Can a Gynecologist Test for STDs? And for those who have had a hysterectomy, our article Do You Still Need a Gynecologist After Hysterectomy? explains ongoing care. You can also visit our office at 2846 Stillwell Avenue (Coney Island) or 201 Kings Highway. The goal is to give you care that fits your whole life, not just one visit.

• Your period is suddenly much heavier or longer than usual
• You have severe cramps that do not get better with over-the-counter pain relief
• You miss several periods in a row and are not pregnant
• You notice bleeding between periods or after sex
• You have symptoms that interfere with work, school, or daily activities

Frequently Asked Questions About Menstrual Cycle Phases

Below are answers to common questions about menstrual cycle phases. This information is general education, not a diagnosis. If something feels off, talk to a provider. A Primary Care provider like Stella Geller DO can review your symptoms and help you decide whether a visit to our Gynecology service is the right next step. For many people, an in-person appointment at our 445 Kings Highway office is a good place to start.

• How long is a normal cycle? A typical cycle lasts 21 to 35 days, counting from the first day of one period to the first day of the next. According to ACOG, cycles can vary from person to person and month to month. MedlinePlus also notes that a cycle length outside this range may still be normal for some people.
• What are the four phases? The menstrual phase, follicular phase, ovulation, and luteal phase. Each phase involves changes in estrogen, progesterone, follicle-stimulating hormone, and luteinizing hormone. These hormones prepare the uterus for a possible pregnancy each month.
• What symptoms are common during each phase? Mild cramps, bloating, breast tenderness, fatigue, and mood changes can occur, especially before or during the period. These symptoms are usually manageable. Severe pain, very heavy bleeding, or symptoms that interfere with daily life are reasons to check in with a provider.
• When should I see a gynecologist? You should consider a gynecology visit if you have periods that last more than seven days, bleeding between periods, missed periods, or pelvic pain that does not go away. These can be signs of conditions that need evaluation.
• Can stress or lifestyle changes affect my cycle? Yes. Stress, illness, major weight changes, and travel can shift the timing of your cycle. If your cycle stays irregular for several months, it is worth discussing with a provider.

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Sources

• ACOG: Women's Health
• MedlinePlus: Health Topics