Definition for Premenstrual syndrome
From Biology Forums Dictionary
Premenstrual syndrome (PMS) is a collection of emotional symptoms, with or without physical symptoms, related to a woman's menstrual cycle. While most women of child-bearing age (up to 85%) report having experienced physical symptoms related to normal ovulatory function, such as bloating or breast tenderness, medical definitions of PMS are limited to a consistent pattern of emotional and physical symptoms occurring only during the luteal phase of the menstrual cycle that are of "sufficient severity to interfere with some aspects of life".
In particular, emotional symptoms must be present consistently to diagnose PMS. The specific emotional and physical symptoms attributable to PMS vary from woman to woman, but each individual woman's pattern of symptoms is predictable, occurs consistently during the ten days prior to menses, and vanishes either shortly before or shortly after the start of menstrual flow.
Two to ten percent of women have significant premenstrual symptoms that are separate from the normal discomfort associated with menstruation in healthy women.