The time leading up to menopause is called perimenopause. Menopause is when your periods stop. It is also when your ovaries stop making estrogen. Some women reaches at the age of 30 and some in their 60s, but the average age of reaching menopause in the western world is at 51. 

Reaching menopause is a good signal because it informs a woman that it is time to see a health professional to take a look at all the signs a woman are having at and also take at what risk a woman have for disease later on.