From the Research
The follicular, ovulation, and luteal phases are the three main stages of the menstrual cycle, with the most recent and highest quality study 1 providing the most accurate description of these phases. The menstrual cycle is a complex process, and understanding its different phases is crucial for tracking fertility, planning or preventing pregnancy, and monitoring overall reproductive health.
Phases of the Menstrual Cycle
- Follicular phase:
- Begins on the first day of menstruation
- Follicle-stimulating hormone (FSH) stimulates follicle growth in the ovaries
- Estrogen levels rise, causing the uterine lining to thicken
- Ovulation phase:
- Luteinizing hormone (LH) surge triggers the release of an egg from the dominant follicle
- Typically occurs mid-cycle, about 14 days before the next period
- Fertile window lasts about 24-36 hours
- Luteal phase:
- Ruptured follicle becomes the corpus luteum, producing progesterone
- Progesterone maintains the uterine lining for potential implantation
- If no pregnancy occurs, hormone levels drop, triggering menstruation As noted in the study 1, the normal ovulatory menstrual cycle requires the presence of a mature hypothalamic-pituitary-ovarian axis and highly coordinated hormonal feedback loops, resulting in the formation of a mature follicle and release of an oocyte during each cycle, with menses occurring in the absence of fertilization.
Variability in Menstrual Cycle Parameters
The study 2 highlights the variability between women in menstrual cycle parameters, including days of menstrual bleeding, cycle lengths, follicular phase lengths, and luteal phase lengths, related to age and parity.
Clinical Implications
Understanding the phases of the menstrual cycle and their variability is essential for providing appropriate counseling and education to individuals and identifying menstrual abnormalities when they arise, as emphasized in the study 1. In clinical practice, it is essential to consider the individual variability in menstrual cycle parameters and to use the most recent and highest quality evidence, such as the study 1, to inform decision-making and provide personalized care.