Anovulatory cycle
While the normal menstrual cycle in the human typically lasts 4 weeks (28 days, range 24–35 days) and consists of a follicular phase, ovulation, and a luteal phase, followed by either menstruation or pregnancy, the anovulatory cycle has cycle
lengths of varying degrees. In many circumstances, menstrual intervals are prolonged exceeding 35 days leading to oligomenorrhea (cycle >35 – 180 days interval), or even longer, amenorrhea. In other cases, menstruation may be fairly regular (eumenorrhea), or more frequent (intervals < 21 days), or there may be a loss of menstrual pattern (menorrhagia, dysfunctional uterine bleeding).
Common treeshrew
Both sexes of common treeshrews are sexually mature at the age of about three months. In captivity, females give birth for the first time at the age of about 4.5 mo, usually in February. A postpartum oestrus results in more births in April. Their oestrus cycle is eight to 39 days, and the gestation period lasts 40 to 52 days, after which a litter of one to three individuals is born. The newborn offspring weigh about 10 to 12 grams. Females suckle their young every other day, and neglect their young as long as possible. They would not even be able to identify their own young if they did not mark them with the scent produced from glands in their sternum and abdomen. Juveniles leave the nest between 25 and 35 days of age. Longevity of a captive common treeshrew has been recorded as 12 yr and 5 mo.