The Four Phases of the Menstrual Cycle Explained | Complete Nutrition

Female health

The four hormonal phases of the menstrual cycle

Most women know the menstrual cycle has phases but few learn what is actually happening in each one. The cycle is more interesting than the simplified version most people hear. Different hormones dominate at different times, producing real changes in mood, energy and how you feel. Knowing the pattern helps you work with your cycle rather than constantly being surprised by it.

Visit the Female Health Hub

Updated:
May 2026

Written by:
Dominic Walton, MD

Reading time:
6 min

Phase one

The menstrual phase

The cycle starts on the first day of your period. The bleeding marks the end of the previous cycle and the start of the new one.

What is happening

The uterine lining (endometrium) that built up over the previous cycle is being shed because no pregnancy occurred. Oestrogen and progesterone are at their lowest levels of the cycle. The brain is starting to send signals to the ovaries to begin developing the next batch of eggs. The drop in hormones causes the actual shedding of the lining.

How long it lasts

Most periods last 3 to 7 days. Flow is typically heavier in the first 1 to 2 days and lighter toward the end. Total blood loss is usually 30 to 80 ml across the period, though women generally do not measure this directly. Significant variation between cycles is common and within the normal range.

How you might feel

Many women feel tired and a bit low energy in the first day or two of their period due to the very low hormone levels. Cramps from uterine contractions can produce discomfort. As the period progresses oestrogen starts to rise again, which often produces gradually improving mood and energy. Some women feel quite good by the end of their period.

Practical points

You can train, work and do everything else during your period if you feel up to it. Heat, gentle movement and over the counter pain relief help with cramps. Iron rich foods or supplements may help women with heavier periods. Significant pain that interferes with life is not normal and warrants medical assessment.

Phase two

The follicular phase

The follicular phase runs from the end of your period to ovulation. This is when oestrogen is rising and most women feel at their best.

What is happening

A group of egg containing follicles is developing in the ovaries. Each follicle produces oestrogen as it develops. One follicle becomes dominant and continues to mature while the others are reabsorbed. Oestrogen rises steadily through this phase. The uterine lining is rebuilding in preparation for a potential pregnancy.

How long it lasts

The follicular phase typically lasts 10 to 14 days but is the most variable part of the cycle. Women with longer cycles usually have longer follicular phases. The phase ends with ovulation. The variability in cycle length comes mostly from variation in this phase, not in the second half.

How you might feel

Rising oestrogen typically produces good energy, stable mood, better sleep, sharper thinking and increased libido. Many women report feeling at their best in the days approaching ovulation. Strength training and high intensity work often feel particularly good in this phase. This is the more biologically friendly half of the cycle for most women.

Practical points

If you have specific goals like a personal best in training or an important presentation, the follicular phase tends to be the best time to attempt them. Skin tends to be at its best. Sleep is usually easier. None of this is a strict rule but the pattern is consistent enough that many women plan around it.

Phase three

Ovulation

Ovulation is the brief midpoint of the cycle when an egg is released. It is a moment rather than a phase but it has its own characteristic features.

What is happening

The pituitary gland releases a surge of LH (luteinising hormone) that triggers the mature follicle to release its egg. The egg travels into the fallopian tube where it can be fertilised over the next 12 to 24 hours. Oestrogen is at its peak. Cervical mucus becomes clear and stretchy to help sperm reach the egg.

When it happens

Ovulation typically happens 12 to 14 days before the next period rather than 14 days after the previous one. In a regular 28 day cycle this is around day 14. In a 30 day cycle it is around day 16. Some women feel a slight pain on one side at ovulation (mittelschmerz). Some notice changes in cervical mucus or a slight rise in basal body temperature after ovulation.

How you might feel

Peak oestrogen levels around ovulation typically produce good mood, energy and libido. Some women feel particularly social, confident or sexual around this time. Cervical mucus changes can be noticeable. Mid cycle pain or a slight bleed can occur. Most women feel reasonably well around ovulation.

Practical points

The day before and day of ovulation are the most fertile days of the cycle. Tracking ovulation through changes in mucus, temperature or LH testing helps if you are trying to conceive. Apps that predict ovulation are estimates rather than guarantees. Ovulation does not always happen at the predicted day even in regular cycles.

Phase four

The luteal phase

The luteal phase runs from ovulation to the next period. This is when PMS happens and when most cycle related symptoms occur.

What is happening

After releasing the egg, the empty follicle becomes a structure called the corpus luteum which produces progesterone. Progesterone prepares the uterine lining for a potential pregnancy. Oestrogen has a smaller second peak in the early luteal phase. If pregnancy does not occur the corpus luteum breaks down, hormones drop and the next period starts.

How long it lasts

The luteal phase is relatively consistent at 12 to 14 days. Variation in total cycle length comes mostly from the follicular phase rather than this one. A consistently short luteal phase (less than 10 days) can indicate hormonal issues that affect fertility.

How you might feel

Many women feel fine in the first week of the luteal phase. Body temperature is slightly higher. Sleep can suffer. Energy may be somewhat lower than the follicular phase. The second week (the week before your period) is when PMS hits for women who have it. Mood changes, breast tenderness, bloating, food cravings, sleep disruption and irritability are all common.

Practical points

Adjust expectations of yourself in the second half of the luteal phase if you are someone affected by PMS. Lighter training, more rest, easier nutrition and being kind to yourself all help. Significant PMS that affects life can be treated. Severe symptoms (PMDD) need medical attention. Speak to your GP if your premenstrual week is making your life hard.

The phases of the menstrual cycle sit at the heart of the female health library alongside guides on hormones, fertility and conditions that affect cycles. For the full female health catalogue see our Female Health hub.

Part of the hub

Back to the Female Health Hub

This guide sits inside our female health library covering hormones, cycles, fertility, menopause and the conditions women face across the lifespan. Head back to the hub for the full catalogue.

Visit the Female Health Hub

Keep reading

More on female health

For the broader cycle picture our The Menstrual Cycle: A Complete Guide covers the full topic. The Key Hormones That Drive Female Health covers the hormones at play. And Premenstrual Syndrome: A Complete Guide covers PMS specifically.

Frequently asked

Menstrual cycle phase questions

How long is each phase?

The menstrual phase typically lasts 3 to 7 days. The follicular phase 10 to 14 days. Ovulation is a moment rather than a phase. The luteal phase is consistently 12 to 14 days. Total cycle length variation comes mostly from variation in the follicular phase.

When am I most fertile?

The few days before and the day of ovulation. Sperm survive several days while the egg only survives about a day. Regular intercourse 2 to 3 times a week through your cycle covers the fertile window without requiring precise timing.

Why do I feel best mid cycle?

Rising oestrogen approaching ovulation typically produces good energy, stable mood, better sleep, sharper thinking and increased libido. Many women feel at their best in the days leading up to ovulation. This is biological rather than coincidence.

Why do I feel rough before my period?

The week before your period is the late luteal phase when progesterone has been high for a while and is starting to fall. The combination of rising fall and the imbalance with oestrogen produces PMS symptoms in many women. Mood changes, bloating, breast tenderness and irritability are common.

Should I train less in the luteal phase?

Not necessarily. Many women train well across the cycle. Some find heavy work harder in the late luteal phase due to sleep disruption and PMS. Adjust by how you feel rather than following a rigid rule. Lighter sessions or more rest in your premenstrual week can help if you struggle then.

What is a short luteal phase?

A luteal phase shorter than 10 days. This can indicate progesterone production issues that affect fertility. The condition is called luteal phase defect and may benefit from treatment. Speak to your GP if you are trying to conceive and notice consistently short luteal phases.

Can I tell when I am ovulating?

Many women notice changes in cervical mucus (becomes clearer and stretchy), a slight pain on one side, increased libido or other subtle signs around ovulation. Ovulation prediction kits detect the LH surge before ovulation. Tracking basal body temperature shows the rise that follows ovulation. None of these methods are perfectly reliable but they give useful information.