A woman undergoes a few medically significant stages through the course of her life. A girl is born with a fixed number of oocytes or potential ova which can all become children. These female reproductive cells remain quiescent until shaken awake by the powerful nudges by the new team of various very powerful hormones at an age of around 10 to 12 depending on her nutritional and fitness level.
Puberty is a slow process and takes a few years to stabilize into fairly stable cycle to remain so for a very long time. She under goes a lot of changes during this period. The embryonic female eggs starting developing and one day it is released from one over the ovaries. The preparations the uterus has made to receive the fertilized ovum and nurture it to a child goes waste and sheds its degenerating lining with some blood. That time is the first of her periods.
Menopause and its symptoms
The last of the significant changes a woman undergoes is the complete reversal of the very first one she had. As the woman approaches the ages around 49 to 52 years, this process starts to reverse.
Menopause by convention is defined to have occurred if the woman does not have a period continuously for a year. It marks the very last ovulation.