Menstruation
Menstruation is the most visible phase of the menstrual cycle and its beginning is used as the marker between cycles. The first day of menstrual bleeding is the date used for the last menstrual period (LMP). The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women, and 21 to 31 days in adults (an average of 28 days).
Cougar
Females reach sexual maturity between one-and-a-half to three years of age. They typically average one litter every two to three years throughout their reproductive lives, though the period can be as short as one year. Females are in estrus for about 8 days of a 23-day cycle; the gestation period is approximately 91 days. Females are sometimes reported as monogamous, but this is uncertain and polygyny may be more common. Copulation is brief but frequent. Chronic stress can result in low reproductive rates when in captivity as well as in the field.