Cycle Basics

The menstrual cycle is a natural process that prepares the body for a possible pregnancy. It starts on the first day of bleeding and ends the day before the next period. A typical cycle lasts about 28 days, but anywhere between 21 and 35 days can be normal.

The cycle has four main phases.

Menstrual phase Bleeding occurs as the uterine lining is shed. It usually lasts 3 to 7 days.

Follicular phase The body prepares for ovulation. Energy and mood often improve gradually.

Ovulation phase An egg is released and can be fertilized for a short time. This is the most fertile period.

Luteal phase After ovulation, the body prepares for pregnancy or the next period. Some people feel fatigue or mood changes.

Every cycle is unique. Changes are common during adolescence or stress. See a healthcare professional if you have severe pain, very heavy bleeding, or very irregular cycles.

Knowing your cycle helps you anticipate periods, understand body signals, and take better care of your health.