Estrogen and progesterone are the primary hormones responsible for regulating the menstrual cycle and thus, initiating periods. These hormones, produced in the ovaries, work together to control the various phases of the cycle. Other hormones, such as luteinizing hormone (LH) and follicle-stimulating hormone (FSH), from the pituitary gland and the hypothalamus also play crucial roles in this complex process.
The Role of Key Hormones in Menstruation
- Estrogen: This hormone is crucial for building up the uterine lining (endometrium) in preparation for a potential pregnancy. A drop in estrogen levels triggers the shedding of the uterine lining, resulting in menstruation. [Source: Saint Luke's Health System, UCSF Health, Yale Medicine]
- Progesterone: Produced after ovulation, progesterone helps maintain the uterine lining. If pregnancy doesn't occur, progesterone levels drop, contributing to the onset of menstruation. [Source: Saint Luke's Health System, UCSF Health]
- Luteinizing Hormone (LH): This hormone triggers ovulation, the release of an egg from the ovary. LH levels fluctuate throughout the menstrual cycle. [Source: Merck Manual]
- Follicle-Stimulating Hormone (FSH): This hormone stimulates the growth of follicles in the ovaries, which contain the eggs. [Source: Merck Manual]
While estrogen and progesterone are the most directly involved in the menstruation process itself, a proper balance and interplay of all these hormones are necessary for a regular menstrual cycle. Hormonal imbalances can lead to irregular periods or other menstrual problems. [Source: UpToDate, Progressive Women's Health Online]
Hormones and Menstrual Irregularities
Irregular periods are often a sign of a hormonal imbalance. Conditions like polycystic ovary syndrome (PCOS) can significantly disrupt the hormonal balance, affecting the regularity of menstruation. [Source: UpToDate, Yale Medicine]
