Which Hormone Causes Periods?

Menstruation

Menstruation, commonly referred to as a “period,” is primarily controlled by the interaction of several hormones within the female reproductive system. The key hormones involved in regulating the menstrual cycle are:

  • Follicle-Stimulating Hormone (FSH): FSH is produced by the anterior pituitary gland in the brain. It plays a crucial role in the early stages of the menstrual cycle. FSH stimulates the growth and maturation of follicles (fluid-filled sacs containing immature eggs) in the ovaries.
  • Luteinizing Hormone (LH): LH, also produced by the anterior pituitary gland, works in conjunction with FSH. It triggers the release of a mature egg (ovulation) from one of the ovarian follicles during the middle of the menstrual cycle.
  • Estrogens: Estrogens, primarily estradiol, are produced by the developing ovarian follicles. They have a variety of effects on the female reproductive system, including stimulating the thickening of the uterine lining (endometrium) in preparation for potential implantation of a fertilized egg.
  • Progesterone: Progesterone is produced by the corpus luteum, a structure that forms in the ovary after ovulation. It plays a critical role in preparing the uterine lining for potential pregnancy. If pregnancy does not occur, progesterone levels decrease, leading to the shedding of the uterine lining, which results in menstruation.
  • Gonadotropin-Releasing Hormone (GnRH): GnRH is released by the hypothalamus in the brain, and it controls the secretion of FSH and LH from the pituitary gland. GnRH release is pulsatile and changes throughout the menstrual cycle.

The menstrual cycle is a complex, tightly regulated process that involves the interplay of these hormones. It typically lasts around 28 days, although it can vary from person to person. The cycle begins on the first day of menstruation (the start of the period) and continues until the start of the next period.

If fertilization and implantation of an embryo do not occur, progesterone levels drop, triggering the shedding of the uterine lining, which is expelled from the body as menstrual bleeding. This marks the start of a new menstrual cycle.

If you have concerns or questions about your menstrual cycle or experience irregularities, it’s advisable to consult with a healthcare provider or gynecologist for evaluation and guidance.

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