https://my.clevelandclinic.org/h ... 132-menstrual-cycle
How long is a normal menstrual cycle?
The average length of a menstrual cycle is 28 days. However, a cycle can range in length from 21 days to about 35 days and still be normal.
女性正常的月经周期是多长?
月经周期的平均长度为28天。 然而,一个周期的长度可以从 21 天到大约 35 天不等,但仍然是正常的。