Menstrual Cycle Phases: The Four Stages at a Glance

What are the four phases of the menstrual cycle?

In order, the four phases usually described are:

1. Menstruation: your period, starting on day 1.
2. The follicular phase: from day 1 to ovulation, while an egg matures. It overlaps with your period.
3. Ovulation: the release of an egg from an ovary.
4. The luteal phase: from ovulation to the day before your next period.

Researchers often describe the same cycle as two phases, follicular and luteal, divided by ovulation, with the period counted as the start of the follicular phase. The four-phase version simply gives the period and ovulation their own names. A cycle runs from the first day of one period to the day before the next. The NHS says the average is around 28 days, and that regular cycles from 21 to 35 days are normal.

This page is the overview. For the detail, see the follicular phase, the luteal phase and cervical mucus through the cycle.

Menstrual cycle phases chart: days, hormones and what you notice

The days below assume a regular 28-day cycle, the textbook example. Real cycles vary, as the section after the phases explains. To estimate your own dates, try the period predictor or the ovulation and fertile window calculator.

Phase 1: menstruation

A period is blood and womb lining leaving the body because no pregnancy has started and oestrogen and progesterone levels have fallen. The NHS says periods last between 2 and 7 days, usually about 5, with the heaviest bleeding in the first 2 days, and that you lose about 20 to 90ml of blood. In a 2019 study of 612,613 app-tracked cycles, the average bleed lasted 4.0 days.

Phase 2: the follicular phase

Follicle-stimulating hormone (FSH) from the pituitary gland makes several follicles in the ovary grow. One becomes dominant and produces rising oestrogen, which thickens the womb lining and changes cervical mucus. This is the phase whose length varies: in the 2019 data it averaged 15.2 days in 25- to 30-day cycles and 26.8 days in 36- to 50-day cycles. More on the follicular phase.

Phase 3: ovulation

When oestrogen has been high for long enough, the pituitary releases a surge of luteinising hormone (LH) and the dominant follicle releases its egg. The American College of Obstetricians and Gynecologists (ACOG) says an egg can survive in the fallopian tube for about 24 hours, and sperm for about 3 days, sometimes up to 5; the NHS says sperm can survive for up to 7 days. ACOG puts the fertile window at 5 days before ovulation to 1 day after. Signs include slippery, stretchy mucus and, for some people, ovulation pain; how to track ovulation compares the ways to pin it down.

Phase 4: the luteal phase

The emptied follicle becomes the corpus luteum, which makes progesterone and oestrogen. Progesterone prepares the womb lining for a possible pregnancy and raises your resting temperature, by 0.5 to 1°F (roughly 0.3 to 0.6°C) according to ACOG. The NHS says the time from the release of an egg to the start of a period is around 10 to 16 days. If no pregnancy starts, the corpus luteum breaks down, hormone levels fall and the next period begins. More on the luteal phase.

How the phases change with cycle length and age

The 28-day cycle is an average, not a rule. In the 2019 study only 13% of cycles were exactly 28 days long, and even in those the follicular phase averaged 15.4 days. In cycles of 21 to 50 days the luteal phase averaged between 11.0 and 12.9 days, while the follicular phase ranged from 12.4 to 26.8. The study used data from Natural Cycles app users and was funded by the company.

• In teenagers: ACOG, the US college, says periods normally come every 21 to 45 days and can take about 1 to 2 years after the first period to become regular.
• With age: cycles shorten, mostly through a shorter follicular phase. In the 2019 data the average cycle fell from 30.3 days at ages 18 to 24 to 27.4 days at 40 to 45.
• Between cycles: the NHS says it is common for periods to come more or less often than every 28 days, anywhere from every 21 to every 35 days.

Moods, symptoms and food across the cycle

Mood and physical symptoms cluster in the luteal phase. The NHS describes premenstrual syndrome (PMS) as symptoms in the weeks before a period. The most common include mood swings, feeling irritable, anxious or emotional, tiredness, bloating, breast tenderness, headaches and food cravings, and the NHS says they usually improve when your period starts and disappear a few days afterwards. If your period is late, see PMS or pregnancy symptoms.

Phase-based eating plans, sometimes called cycle syncing, are popular, but none of the sources on this page recommends eating differently in each phase. For premenstrual symptoms, the NHS advises a healthy, balanced diet, perhaps as smaller meals every 2 to 3 hours. In the US, ACOG suggests complex carbohydrates, calcium-rich foods, less fat, salt and sugar, and avoiding caffeine and alcohol.

When to see a GP

The NHS advice:

• changes in your periods, such as lasting longer or getting lighter, do not necessarily mean there is a problem but do need to be investigated by a GP or a women's or contraceptive clinic
• bleeding between periods, after sex or after the menopause needs to be checked by a doctor
• if you have missed 3 periods in a row and a pregnancy test is negative, see a GP
• if PMS is affecting your daily life or lifestyle changes have not helped, a GP can advise on treatments

If you are trying to conceive and your cycles are irregular, see irregular periods and trying to conceive.

Frequently asked questions

What are the phases of the menstrual cycle in order?

Menstruation (your period), the follicular phase, ovulation and the luteal phase. The follicular phase starts on day 1 alongside the period and lasts until ovulation; the luteal phase runs from ovulation to the day before the next period, when the cycle starts again. In a 28-day cycle, ovulation comes about 14 days before the next period.

Which hormones control each phase of the menstrual cycle?

FSH from the pituitary gland drives the follicular phase, and the growing follicles make oestrogen. Sustained high oestrogen triggers a surge of luteinising hormone (LH), which causes ovulation. In the luteal phase the corpus luteum makes progesterone and oestrogen; when both fall, the womb lining is shed and a period starts.

How does discharge change in each phase?

The NHS says vaginal secretions change through the cycle, becoming thinner and stretchy, a bit like raw egg white, around ovulation. ACOG says mucus increases and turns thin and slippery just before ovulation, then decreases and thickens just after. Outside the days around ovulation it is typically thick and scant.

What is the release of an egg called?

Ovulation. The NHS defines it as the release of an egg from the ovaries and says one egg usually develops and is released in each cycle. Occasionally more than one is released, and if more than one is fertilised it can lead to twins. In a 28-day cycle, ACOG says it happens about 14 days before the next period.