From the Guidelines
The female menstrual cycle typically consists of four main stages: the menstrual phase, follicular phase, ovulation, and luteal phase. The menstrual phase begins on day 1 with the shedding of the uterine lining, lasting about 3-7 days. Next is the follicular phase, overlapping with menstruation, when follicle-stimulating hormone (FSH) stimulates follicle development in the ovaries and estrogen levels rise to rebuild the uterine lining. This phase lasts until ovulation, which occurs around day 14 in a 28-day cycle when luteinizing hormone (LH) surges, causing the release of a mature egg from the ovary. Finally, the luteal phase follows ovulation and lasts about 14 days, during which the ruptured follicle forms the corpus luteum, producing progesterone to maintain the thickened uterine lining in preparation for possible implantation. If pregnancy doesn't occur, the corpus luteum degenerates, hormone levels drop, and the cycle begins again with menstruation. These hormonal fluctuations throughout the cycle cause various physical and emotional changes that many women experience monthly, as noted in studies on menstrual cycles and fertility 1. It's worth noting that the probability of pregnancy is increased when the menstrual cycle is outside the range of 26–32 days, even if unprotected sexual intercourse is avoided on days 8–19, as discussed in the context of contraceptive use 1. However, the general stages of the menstrual cycle remain consistent, with variations in cycle length and fertility window timing among individuals. In clinical practice, understanding these stages is crucial for addressing menstrual irregularities and providing appropriate guidance on fertility and contraception, as emphasized in guidelines for contraceptive use 1. Key points to consider in real-life clinical medicine include:
- The menstrual cycle can vary in length and fertility window
- Hormonal fluctuations cause physical and emotional changes
- Understanding the stages of the menstrual cycle is essential for addressing menstrual irregularities and providing guidance on fertility and contraception.