The 4 Phases of Your Menstrual Cycle Explained

Q: What are the 4 phases of the menstrual cycle?

The four phases of the menstrual cycle are: (1) Menstrual phase — days 1–5, when the uterine lining sheds. (2) Follicular phase — days 1–13, when follicles develop and estrogen rises. (3) Ovulation — around day 14, when the egg is released. (4) Luteal phase — days 15–28, when progesterone rises to prepare for possible pregnancy.

Q: How long is the luteal phase?

The luteal phase is typically 12–16 days long and is the most consistent phase of the cycle. If the egg isn't fertilised, the corpus luteum breaks down, progesterone drops, and menstruation begins.

Q: What hormones control the menstrual cycle?

The four key hormones are: FSH (follicle-stimulating hormone), which triggers follicle development; estrogen, which builds the uterine lining; LH (luteinising hormone), which triggers ovulation; and progesterone, which supports the luteal phase and potential pregnancy.

Q: Why does the menstrual cycle change length?

The follicular phase (before ovulation) can vary in length, making cycles shorter or longer. Stress, illness, exercise, weight changes, and hormonal conditions can delay or advance ovulation, shifting the whole cycle length.

The menstrual cycle is a monthly hormonal sequence that prepares your body for potential pregnancy. It's controlled by four key hormones — FSH, estrogen, LH, and progesterone — working in a precisely timed cascade. Understanding each phase helps you make sense of mood changes, energy levels, physical symptoms, and everything in between.

Average cycle length: 28 days (but 21–35 days is normal). Day 1 is always the first day of your period (full flow, not just spotting).

Phase 1

Menstrual Phase

Days 1–5 (average)

The menstrual phase begins on day 1 of your period — the day full bleeding starts. If the egg from the previous cycle wasn't fertilised, the drop in progesterone signals the uterus to shed its lining. This shedding is your period.

Hormones

Estrogen — low Progesterone — low FSH — beginning to rise

How you might feel

Cramping from prostaglandins triggering uterine contractions
Fatigue, lower back pain, bloating
Energy may be lower — this is a natural time for rest
Mood may be lower as progesterone and estrogen are at their lowest

Phase 2

Follicular Phase

Days 1–13 (overlaps with menstrual phase)

The follicular phase actually begins on day 1 alongside menstruation, but its effects really become prominent once bleeding ends. FSH (follicle-stimulating hormone) signals multiple follicles in your ovaries to start developing. One dominant follicle will mature and eventually release an egg. As follicles grow, they produce estrogen — which rises steadily throughout this phase.

Hormones

Estrogen — rising Progesterone — low FSH — rising then falling as dominant follicle takes over

How you might feel

Energy gradually increases as estrogen rises
Improved mood, confidence, and cognitive sharpness
Cervical mucus transitions from dry → sticky → creamy → egg-white (peak fertility sign)
Skin often clearest in this phase
Libido beginning to increase towards end of this phase

Variable phase: This is the phase that varies most between cycles. Stress, illness, and lifestyle can make it shorter or longer — which is why cycles change length.

Phase 3

Ovulation

Around Day 14 (varies)

Once estrogen reaches a peak threshold, it triggers a sudden LH surge — a massive spike in luteinising hormone. Within 24–36 hours, the dominant follicle ruptures and releases a mature egg into the fallopian tube. The egg is viable for just 12–24 hours. Sperm can survive 3–5 days, so the fertile window extends to the 5 days before ovulation plus ovulation day itself.

Hormones

Estrogen — peak LH — surge (24–48 hrs) Progesterone — just beginning to rise

Signs of ovulation

Egg-white cervical mucus — clear, stretchy, slippery
Mild one-sided pelvic pain (mittelschmerz)
Breast tenderness
Heightened libido — peaks around ovulation
Light spotting in some women
BBT rise of ~0.2°C the morning after ovulation

Phase 4

Luteal Phase

Days 15–28 (most consistent phase)

After ovulation, the empty follicle (now called the corpus luteum) produces progesterone. This hormone thickens the uterine lining and prepares the body for potential implantation. If the egg is fertilised and implants, the corpus luteum continues producing progesterone to support early pregnancy. If not, the corpus luteum breaks down around day 25–27, progesterone drops, and the cycle resets with menstruation.

Hormones

Estrogen — falling Progesterone — high then dropping LH — falling

How you might feel

Energy may decline as progesterone has a sedative effect
Bloating, breast tenderness, headaches
PMS symptoms emerge in the final 5–7 days as progesterone drops
Increased appetite and food cravings (lower serotonin drives carb cravings)
Sleep may be more disrupted (progesterone raises body temperature)
Mood may dip, especially in the week before your period

Consistent phase: The luteal phase length is typically 12–16 days and doesn't usually vary much between cycles. If your luteal phase is consistently shorter than 10 days, it may affect fertility (luteal phase defect).

How the 4 Hormones Work Together

FSH (follicle-stimulating hormone): Made by the pituitary gland. Signals follicles to develop at the start of the cycle.
Estrogen: Made by the developing follicles. Builds the uterine lining and triggers the LH surge at its peak.
LH (luteinising hormone): Made by the pituitary gland. Surges at mid-cycle to trigger ovulation.
Progesterone: Made by the corpus luteum after ovulation. Maintains the uterine lining for potential implantation; drops to trigger menstruation if pregnancy doesn't occur.

Track Every Phase of Your Cycle — Free

WomensPal identifies your cycle phases in real time — so you always know where you are and what to expect next.

Start tracking free →

Frequently Asked Questions

What are the 4 phases of the menstrual cycle?

The four phases are: (1) Menstrual — the uterine lining sheds. (2) Follicular — follicles develop and estrogen rises. (3) Ovulation — the egg is released. (4) Luteal — progesterone rises to prepare for possible pregnancy.

How long is the luteal phase?

The luteal phase is typically 12–16 days and is the most consistent phase. If the egg isn't fertilised, the corpus luteum breaks down, progesterone drops, and menstruation begins.

What hormones control the menstrual cycle?

Four key hormones: FSH triggers follicle development; estrogen builds the uterine lining; LH triggers ovulation; progesterone supports the luteal phase and potential pregnancy.

Why does the menstrual cycle change length?

The follicular phase (before ovulation) varies in length, making cycles shorter or longer. Stress, illness, exercise, weight changes, and hormonal conditions can delay or advance ovulation, shifting cycle length.