What causes prolongation of the menstrual cycle in perimenopause?

From the Guidelines

The menstrual cycle becomes longer by a few days in perimenopause primarily due to irregular ovulation caused by declining ovarian function, which leads to a lengthened follicular phase and hormonal fluctuations. During perimenopause, the ovaries produce less estrogen and fewer viable eggs, resulting in cycles where ovulation may be delayed or not occur at all 1. This hormonal fluctuation disrupts the regular pattern of the menstrual cycle, causing the follicular phase to lengthen as the ovaries require more time to develop and release an egg.

• Key factors contributing to the lengthening of the menstrual cycle include:
  • Decreasing levels of inhibin B, a hormone that helps regulate follicle-stimulating hormone (FSH)
  • Higher FSH levels as the body attempts to stimulate the aging ovaries
  • Irregular ovulation and anovulatory cycles
  • Hormonal fluctuations, including changes in estrogen and progesterone levels As women approach menopause, they may experience these changes for 4-8 years before reaching menopause, which is defined as 12 consecutive months without a period. It is essential to consider underlying gynecological problems, such as interactions with other medications, STDs, pregnancy, or new pathologic uterine conditions, which can also contribute to changes in menstrual cycle length 1.

From the Research

Causes of Longer Menstrual Cycle in Perimenopause

The menstrual cycle can be longer by a few days in perimenopause due to several factors, including:

• Hormonal fluctuations: The perimenopause is characterized by wide hormonal fluctuations, with abrupt increases and decreases in estradiol and progesterone levels, often described as a hormonal roller coaster 2.
• Irregular menstrual patterns: The menopausal transition is marked by irregular menstrual patterns, which can lead to longer or shorter menstrual cycles 3.
• Altered responsiveness to gonadal steroid feedback: The perimenopause is characterized by altered responsiveness to gonadal steroid feedback, which can disrupt the normal menstrual cycle 3.
• Gradual loss of oocytes: The perimenopause is marked by the gradual loss of oocytes, which can lead to changes in menstrual cycle length and frequency 3.

Hormonal Changes in Perimenopause

The hormonal changes that occur during perimenopause can have a significant impact on menstrual cycle length, including:

• Wide fluctuations in estradiol and progesterone levels: These fluctuations can lead to changes in menstrual cycle length and frequency 2.
• Decreased inhibin levels: Decreased inhibin levels can lead to increased follicle-stimulating hormone (FSH) levels, which can disrupt the normal menstrual cycle 3.
• Increased FSH levels: Increased FSH levels can lead to changes in menstrual cycle length and frequency 3.

Management of Perimenopausal Symptoms

The management of perimenopausal symptoms, including irregular menstrual cycles, can involve:

• Hormone therapy (HT): HT can be effective in managing perimenopausal symptoms, including irregular menstrual cycles 3, 4.
• Non-hormonal therapies: Non-hormonal therapies, such as lifestyle modifications and alternative therapies, can also be effective in managing perimenopausal symptoms 3.