Premenstrual syndrome (PMS) is a collection of physical, psychological, and emotional symptoms related to a woman's menstrual cycle. While most women (about 80 percent) of child-bearing age have some symptoms of PMS, the official definition limits the scope to having symptoms of "sufficient severity to interfere with some aspects of life". Such symptoms are usually predictable and occur regularly during the two weeks prior to menses. Generally, symptoms may vanish both before or after the start of menstrual flow.