How do I calculate my menstrual cycle? Is the cycle counted starting from the last day of the period until the last day of the following period?
You are close. Day one of your menstrual cycle is the first day of your period. Some time after the first period, called menarche, a woman’s hormone levels more or less stabilize until she approaches menopause.
During those reproductive years, most women menstruate about every 28 days. But we are all different and some women may have longer or shorter cycles, while others may not menstruate each and every month.
The menstrual cycle is based on your body’s preparation for pregnancy. Ovulation, the release of an egg for fertilization, occurs at mid-cycle. Ovulation takes place 14 to 16 days before the start of your next period. The period of fertility is considered to be about a week, because sperm can stay alive for three to four days and the woman’s egg can be fertilized for about a day after it is released from the ovary.
Hormones regulate the changes that occur within the menstrual cycle. After ovulation, hormones signal the uterus to thicken its lining, in preparation for the implantation of a fertilized egg. If pregnancy does not occur, the uterine lining breaks down that extra tissue, which is excreted as blood in your period.