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The menstrual cycle in four phases

Menstrual · follicular · ovulation · luteal at a glance

Day 1

The menstrual cycle

Your cycle runs from the first day of one period to the day before the next one starts. It is the whole loop, not just the bleeding days.

Length varies from person to person, and anything from 24 to 38 days is common. Even for the same person, a few days’ difference month to month is completely normal.

Hormones rise and fall across the cycle and touch a lot of things — skin, sleep, appetite, mood, that bloated feeling. Log for a few months and your own pattern starts to show: "so this is what this part of my cycle is like for me."

Your period

If no pregnancy happens, the thickened lining of the uterus is no longer needed and leaves the body. That is your period. What comes out is not only blood — it is lining tissue and fluid mixed together.

It usually lasts 3 to 7 days. Flow is often heaviest in the first two days, and the colour getting darker toward the end is a normal change too.

Follicular phase

This runs from the first day of your period up to ovulation. Inside your ovaries, several fluid-filled sacs (follicles), each holding an egg, start to grow.

One of them grows largest and gets ready to release its egg. Meanwhile estrogen climbs and the lining of the uterus thickens again.

Many people feel their energy pick up toward the end of this phase. How much you notice varies a lot, so feeling no real difference is not unusual either.

Ovulation

The largest follicle opens and releases its egg. That egg can only be fertilised for about 12 to 24 hours.

Around this time you may notice clear, stretchy discharge, or a light twinge low on one side.

The date shifts from cycle to cycle, and by more than most people expect. In a study of women whose cycles were reliably 28 days, ovulation still landed anywhere from day 10 to day 22. So treat the ovulation date in the app as "the most likely day" rather than a fixed one.

Fertile window

The fertile window is the handful of days when pregnancy is possible. Sperm can survive up to 5 days inside the body and the egg lives about a day after release, which is why the window stretches either side of ovulation.

When ovulation shifts, the window shifts with it. That is why this prediction is a guide and is not suitable for use as birth control.

Luteal phase

This runs from just after ovulation until your next period starts. The site the egg left behind produces progesterone, which keeps the uterine lining in place.

If pregnancy happens, that state continues. If it does not, progesterone drops, the lining comes away, and your period begins.

Bloating, breast tenderness, appetite changes, and mood swings are common in this phase. These are the changes usually called PMS.

Sources

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