Premenstrual syndrome (PMS) (sometimes referred to as PMT or Premenstrual Tension) is a collection of physical, psychological, and emotional symptoms related to a woman's menstrual cycle. While most women of child-bearing age (about 80 percent) have some symptoms of PMS,[1] the official definition limits the scope to having symptoms of "sufficient severity to interfere with some aspects of life".[2] 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.