Hormones During Perimenopause

During perimenopause, which is the transitional phase leading up to menopause, hormone levels in a woman's body begin to change. Perimenopause typically begins in a woman's 40s, although it can start earlier and can last several years until menopause is reached.

The primary hormones involved in perimenopause are oestrogen and progesterone, which are largely controlled by follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

Oestrogen levels during perimenopause can fluctuate widely. Initially, oestrogen levels may be higher or remain relatively stable, but as a woman approaches menopause, oestrogen production decreases. However, these levels can vary significantly from cycle to cycle, leading to irregular menstrual periods.

Progesterone levels also decline during perimenopause. This decline may be more pronounced than the decrease in oestrogen levels. Progesterone is important for regulating the menstrual cycle and preparing the uterus for pregnancy. As progesterone levels decrease, women may experience irregular menstrual periods and changes in the quality of their menstrual flow.

Oestrogen dominance may occur when progesterone levels decrease yet before oestrogen levels decrease. This imbalance may cause irregular or heavy menstrual periods, breast tenderness, mood changes, weight gain and/or fatigue.

Follicle-stimulating hormone (FSH) levels rise during perimenopause as the ovaries become less responsive to its stimulating effects. FSH stimulates the production of oestrogen. Luteinising hormone (LH) levels also increase during this phase. Elevated FSH and LH levels can contribute to irregular menstrual cycles and other perimenopausal symptoms.

During perimenopause, decreased testosterone levels may occur. Thyroid hormone imbalances may also be experienced, which can affect metabolism, energy levels, and overall well-being.

The hormonal fluctuations during perimenopause can give rise to a range of symptoms, including:

• Irregular menstrual periods
• Hot flushes and night sweats
• Mood swings and irritability
• Sleep disturbances
• Vaginal dryness
• Changes in libido
• Weight gain and changes in body composition
• Fatigue and decreased energy levels