What Causes Periods?

Menstruation, commonly referred to as periods, is a natural physiological process that occurs in individuals with a female reproductive system. It involves the shedding of the uterine lining, which occurs approximately once a month. The menstrual cycle is regulated by a complex interplay of hormones and involves various stages. Here’s an overview of what causes periods:

  1. Hormonal Regulation: The menstrual cycle is controlled by hormonal changes orchestrated by the hypothalamus, pituitary gland, ovaries, and uterus.
  2. Hypothalamus: At the start of the menstrual cycle, the hypothalamus in the brain releases gonadotropin-releasing hormone (GnRH).
  3. Pituitary Gland: GnRH signals the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
  4. Ovaries: FSH stimulates the growth of follicles (fluid-filled sacs containing eggs) in the ovaries. One of these follicles will become dominant and continue to mature.
  5. Ovulation: Around the middle of the menstrual cycle, typically around day 14 in a 28-day cycle, the surge in LH triggers ovulation. The mature follicle ruptures, releasing an egg from the ovary into the fallopian tube.
  6. Corpus Luteum Formation: After ovulation, the remnants of the ruptured follicle form the corpus luteum, which secretes progesterone.
  7. Uterine Changes: The increase in progesterone causes the uterine lining (endometrium) to thicken, preparing it to receive a fertilized egg.
  8. Implantation or Shedding: If the egg is fertilized by a sperm and implants in the uterus, pregnancy occurs. If fertilization doesn’t occur, the corpus luteum degenerates, leading to a drop in progesterone levels.
  9. Menstrual Phase: The drop in progesterone triggers the shedding of the uterine lining, which is then expelled through the vagina. This process, known as menstruation or a period, typically lasts for a few days.

The menstrual cycle then begins anew with the hypothalamus releasing GnRH, and the cycle continues to repeat, on average, every 21 to 35 days.

The primary purpose of the menstrual cycle is to prepare the body for potential pregnancy by creating an optimal environment for fertilization and implantation. If pregnancy doesn’t occur, the uterine lining is shed as a period. Hormonal fluctuations during the menstrual cycle can lead to a variety of physical and emotional changes, which can include mood swings, breast tenderness, bloating, and more.

It’s important to note that variations in menstrual cycles are normal and can be influenced by factors such as stress, nutrition, exercise, medical conditions, and age. If you have concerns about your menstrual cycle, it’s advisable to consult a healthcare provider for guidance and evaluation.