All changes occurring in the female body during the menstrual cycle, aimed at creating conditions for conception. In the first phase is the maturation of the follicle, the rupture of its walls and the release of a ready for fertilization egg. In the second — on the site of the ruptured follicle forms a "yellow body" and produces progesterone — a hormone necessary to maintain pregnancy. Under its influence there is a thickening of the inner lining of the uterus (endometrium) so that it becomes possible attachment of the fertilized egg.
Regardless of whether conception occurred or not, you need to know when was the beginning of the cycle. If the pregnancy, her period will be counted from that day. If conception was not knowing the first days of two cycles, we can calculate the interval between them. Normally it is from 21 to 35 days. In healthy women, the length of menstrual cycles is approximately the same, the deviation may be no more than 3-4 days in the big or smaller party.
The external manifestation of the beginning of the new cycle are bleeding from vagina — menstruation. The day that begins profuse bleeding is considered the first day of the cycle. For some gynecological diseases such as endometriosis, menstruation is preceded by spotting. It may take a few days before the real bleeding. This period does not apply to the new cycle. Moreover, this is the reason for going to the doctor.
With regular cycle you can easily calculate the date of the next menstruation. Just count from the first day of abundant bleeding, the number of days equal to the length of your cycle. Wait for the next month need to the resulting day (+/- three days).