1. Hormones in a woman’s body start a few eggs growing, and one is released into
one of the tubes that are attached to her womb (see chart above). The egg travels
down the tube on its way to the womb. This takes several days.
2. During this time the lining of the womb is thickening, getting ready in case an egg
is fertilized by a sperm that has traveled up from the vagina after vaginal intercourse.
3. If a sperm reaches the tube at the right time and joins with the egg, and then this
fertilized egg attaches itself to the lining of the womb, the woman becomes pregnant.
But if the egg is not fertilized by sperm, the egg breaks up, and the womb sheds its
thickened lining because it will not be needed that month. The lining passes out of
the body through the vagina.
How are the days of the menstrual cycle counted?
- A menstrual cycle starts with the first day of monthly bleeding.
- The last day of the menstrual cycle is the day before the next monthly bleeding starts.
- For example, if bleeding started on July 1, that is the first day of the menstrual cycle.
- If the menstrual cycle that month is 28 days long, the next monthly bleeding would starts on July 29.
- If this woman usually has 28-day cycles, she can expect monthly bleeding to start again on August 26.
- Most women have menstrual cycles that last between 24 and 35 days.
- The most common length is 28 days.
- But many women have longer or shorter cycles.
- The length of some women’s cycles varies by a few days from month to month.
- All these patterns are normal.