The menstrual calendar or women’s cycle is not the same for all. There are women who have a regular period and usually have a stable ovulation every month and other women who for one reason or another may have an irregular period and their menstrual and ovulation calendar can be altered from one month to the next. A menstrual cycle or menstrual calendar refers to the time frame between the start of one menstruation and the start of the next. 
The rule usually lasts between 3 and 7 days and the menstrual cycle lasts between 21 and 37 days depending on each woman respectively. The menstrual cycles in each woman are different, so the female menstrual calendar will vary from one woman to another since no two bodies are exactly the same.
Changes in women’s menstruation
- A woman should keep track of her menstrual calendar to know if there are changes or if everything is in order and stable. A woman who has a regular menstrual cycle will have the same or very similar calendar every month. On the other hand, a woman with an irregular menstrual cycle, her calendar will be different and will not be able to accurately predict when her next period will be or when is the most appropriate time to conceive children.
- Although there may also be other factors that cause the menstrual calendar to undergo changes and that although a woman has a regular menstruation there are months in which the rule is early or late. These factors that can trigger changes in the menstrual calendar can be: gaining or losing weight, emotional stress, physical stress, a change in diet, anxiety or changes in hormones.
