Menstrual Cycle & Ovulation: Guide to Key Phases
Learn menstrual cycle phases, ovulation timing and common changes. Track patterns, then prepare questions for a healthcare visit; timing varies by person.
Quick highlights
The menstrual cycle is a natural rhythm of the body. Its details can differ from one person to another and from month to month. Understanding the phases can help you notice your own patterns and ask clearer questions at a health appointment.
Cycle length is counted from the first day of one period to the day before the next period begins. Hormones and the uterine lining usually change through several phases, but timing is not the same for everyone.
- Menstruation: the body sheds the uterine lining; day one of bleeding is counted as the first day of the cycle.
- Follicular phase: this begins alongside menstruation as ovarian follicles develop in preparation for ovulation.
- Ovulation: an ovary releases an egg. Timing varies and cannot be pinpointed accurately by a calendar alone.
- Luteal phase: hormones change as the body prepares for a possible pregnancy. If pregnancy does not occur, a new cycle begins.
Cycle length, bleeding, and symptoms can change with age, stress, and life changes. Tracking your periods and symptoms for a few months may help you and your clinician understand your pattern, but it does not replace an assessment when one is needed.
Ask for medical advice if bleeding has a major effect on daily life, pain is severe, or you notice a sudden and ongoing change in your usual pattern. This general information cannot diagnose a condition.
Trusted sources
These general sources informed this article. Ask your care team about information specific to your situation.