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).
Quintaglio Ascension Trilogy
The estrous cycle of female Quintaglios is 18 thousand days, and a female will hopefully mate 4 times in her lifetime every cycle, normally. There are some exceptions though, as Natova, and one of her daughter with Afsan, arose when 16 thousand days old. Also some females will often at the estrous cycle, thus having very low fertility. While male can mate at almost anytime, they have to wait for a chance, when a female is currently about to enter the cycle and accept the invitation. Females do not have to stick with one male every time, instead, they follow their instinct and choose the right spouse for the moment. Despite living on their own territory, the Quintaglios often have a long lasting friendship with the previous spouses, with the possibility of some forms of pair bonding.