1. Average age: The average age of natural menopause is 51.4 years, with most women experiencing it between 49 and 52 years. 

2. Duration: Menopause typically lasts 2 to 3 years and should occur within a 45 to 55-year age range. 

3. Ovarian function: Ovarian function peaks for about 30 years and starts declining after age 40.

Around 95% of women experience menopause before age 55. 

4. Hormonal factors: Estrogen levels play a significant role in menopause. Hormone fluctuations can influence the timing of menopause. 

5. Other influences: Genetic factors, social pressure, geographical and climatic conditions, smoking, and family/psychological factors also impact menopause.