The menstrual cycle is an intricate series of events that occurs monthly, preparing a woman's body for a possible pregnancy. If pregnancy does not take place, this cycle leads to a menstrual period. It involves fluctuations in hormone levels, as well as changes in the uterus and ovaries. While the length of the menstrual cycle can differ from one person to another, it typically lasts around 28 to 30 days. A woman’s menstrual cycle begins with her first period, which usually happens between the ages of 9 and 15. In the early stages of menstrual cycle, these cycles are often irregular, but they tend to become more regular over time. This cycle repeats every month until menopause, which usually occurs when a woman is in her 40s or 50s.
The uterine cycle and ovarian cycle each consist of several stages, during which various events take place. In the uterine cycle, there are three main phases: the menstrual phase, the proliferative phase, and the secretory phase, which occurs just before bleeding starts. On the other hand, the ovarian cycle also has three phases: the follicular phase, which happens before ovulation, the ovulation phase when an egg is released from an ovary, and the luteal phase, which follows ovulation.
There are three main phases in this cycle:
Menstruation is the first phase of the uterine cycle and marks the beginning of a new menstrual cycle, starting on the first day of noticeable bleeding and typically lasting from 3 to 8 days, with an average of about 5 to 6 days. During this time, the body sheds the thickened lining of the uterus (the endometrium) that was built up in the previous cycle, as there is no pregnancy. Menstrual cycle hormones levels, particularly estrogen and progesterone, are at their lowest, which triggers this shedding. Many people experience symptoms such as cramps, fatigue, and mood swings during this phase, making it a key indicator of reproductive health and signaling the normal functioning of the menstrual cycle.
During this menstrual cycle phase, the uterine lining (endometrium) begins to thicken and regenerate in preparation for a possible pregnancy. This thickening occurs as a result of increased levels of estrogen produced by the ovaries. As the tissues grow, they become rich in blood vessels and nutrients to provide support for a fertilized egg should conception occur. Typically lasting from about the end of the period to just before ovulation, this phase can vary in length but usually spans around 7 to 14 days. As the lining builds up, ovarian follicles also develop, leading to the release of an egg during ovulation. This phase is crucial for creating a suitable environment for potential implantation of an embryo. The proliferative phase highlights the body’s readiness for reproduction and is characterized by physiological changes in the uterus that prepare it for the possibility of pregnancy.
Typically lasting about 14 days, this phase begins as the corpus luteum (the structure formed from the follicle that released the egg) secretes hormones, primarily progesterone, along with some estrogen. Progesterone plays a vital role during this phase by causing the uterine lining (endometrium) to thicken further and become more vascular and glandular, creating a nurturing environment ready to support a fertilized egg. If fertilization occurs, the menstrual cycle hormones help maintain the uterine lining for early pregnancy. However, if the egg is not fertilized, the corpus luteum breaks down, leading to a decrease in progesterone and estrogen levels. This drop in hormones triggers the breakdown of the uterine lining, resulting in menstruation and the start of a new cycle. The secretory phase is essential for preparing the uterus for potential implantation and nourishing a developing embryo if conception occurs.
There are also three phases in this cycle:
The follicular phase is the first phase of the ovarian cycle, starting on the first day of menstruation and continuing until ovulation. This phase typically lasts anywhere from about 10 to 22 days, depending on the individual’s cycle. During the follicular phase, the pituitary gland in the brain releases a hormone called follicle-stimulating hormone (FSH), which stimulates the ovaries to develop multiple follicles, each containing an immature egg. As these follicles grow, one becomes dominant and continues to mature, while the others stop developing. This dominant follicle produces increasing amounts of estrogen, which orchestrates the thickening of the uterine lining in preparation for a possible pregnancy. The rise in estrogen levels also triggers a surge in another hormone called luteinizing hormone (LH), leading up to ovulation.
This menstrual cycle phase begins when the dominant follicle, which has been maturing in the ovaries during the follicular phase, reaches a size of about 2 centimeters. The rising levels of estrogen produced by this follicle lead to a rapid increase in luteinizing hormone (LH) from the pituitary gland, known as the LH surge. This surge triggers the follicle to rupture and release a mature egg into the fallopian tube, where it can potentially meet sperm for fertilization. Ovulation usually occurs about midway through the cycle and is a key moment for fertility, as it signifies the time when a person is most likely to conceive. After ovulation, the empty follicle transforms into a structure called the corpus luteum, which will play a vital role in the next phase of the ovarian cycle. The ovulation phase is essential for reproduction, marking the point of egg release that can lead to pregnancy.
The luteal phase is the final phase of the ovarian cycle, lasting about 14 days after ovulation. It begins when the ruptured follicle transforms into the corpus luteum, which produces significant amounts of progesterone and some estrogen. These hormones prepare the uterine lining for a potential pregnancy by thickening and nourishing it to support a fertilized egg. If fertilization occurs, the corpus luteum continues to release hormones to sustain the pregnancy. If not, it degenerates, leading to a drop in menstrual hormone levels that triggers the shedding of the uterine lining and the start of menstruation. The luteal phase is crucial for facilitating reproduction or preparing for the next menstrual cycle.
Related: When Should You Consult a Gynecologist?
Understanding and keeping track of your menstrual cycle is important for a woman’s overall reproductive health. If you notice ongoing issues or significant changes in your cycle, it’s crucial to speak with our best lady gynecologist in Thane at Dr Hiranandani Hospital for tailored advice. Are you concerned that medical issues might be causing your irregular periods? Consider getting diagnosed at Dr Hiranandani Hospital. Trusted by top doctors in India, Dr Hiranandani Hospital offers affordable at-home blood tests and delivers highly accurate reports, supported by advanced laboratory facilities and a team of experienced phlebotomists. Schedule your test today!
