育龄女子周期性的由于子宫内膜剥落、出血和修复变化的一个周期。平均为28天menstrual cycle

• 27岁以下女性在月经周期内怀孕的几率是35岁以上者的2倍。

  The probability that women under 27 will get pregnant in a menstrual cycle is twice that of women over 35.

• 它所带来的最突出问题就是月经周期缩短，经期延长。

  The most prominent issue it causes is a shortening of the menstrual cycle and a lengthening of the period of menstruation.