From the Guidelines
The menstrual cycle is typically divided into four stages: menstruation, the follicular phase, ovulation, and the luteal phase, with the entire cycle lasting around 26-32 days for optimal fertility and regularity, as evidenced by a study of 7,600 menstrual cycles 1. The stages of the menstrual cycle are characterized by distinct physiological changes, including:
- Menstruation: the shedding of the uterine lining, resulting in bleeding, which typically lasts 3-7 days
- The follicular phase: a period of follicle development in the ovaries, stimulated by follicle-stimulating hormone (FSH), and a rise in estrogen levels to rebuild the uterine lining, lasting around 13-14 days
- Ovulation: the release of a mature egg from the ovary, triggered by a surge in luteinizing hormone (LH), occurring around day 14 of a typical 28-day cycle
- The luteal phase: a period of preparation for possible implantation, during which the ruptured follicle forms the corpus luteum, producing progesterone to maintain the thickened uterine lining, lasting around 14 days These stages are influenced by hormonal fluctuations, which can cause various physical and emotional changes, and are affected by the length of the menstrual cycle, with cycles outside the range of 26-32 days potentially impacting fertility, as noted in the study 1. Key factors affecting the menstrual cycle include:
- Cycle length: with optimal fertility and regularity typically occurring within the 26-32 day range
- Hormonal fluctuations: including changes in FSH, LH, estrogen, and progesterone levels
- Physical and emotional changes: such as breast tenderness, mood changes, and changes in cervical mucus consistency, which can vary throughout the cycle.