Premenstrual syndrome (PMS) is a collection of physical, psychological and emotional symptoms, related to women menstrual cycle. PMS occur after womens ovulation and typically end with the onset of menstrual flow. On an average menstruation begins at 12 or 13 years of age and ends with menopause. The typical cycle last for 28 days including 1st day of cycle being the first day of bleeding.
This cycle is divided into following phases:
Follicular phase - it is also called proliferative phase. At this phase endometrium grows and thickens, ovaries produce estrogen, and some of the ovarian follicles are stimulated until their eggs have nearly tripled in size. This phase begins at the end of menstrual flow and lasts for 10-14 days.
Ovulatory Phase - in this phase eggs are released into one of the fallopian tubes. This phase lasts for 36 hours only.
Secretory phase - it is also called as luteal phase. This phase begins when ovulation occurs. During average 14 days of this phase progesterone and estrogen stimulates the uterus lining in preparation for implantation by a fertilized egg.
So PMS is the reoccurring condition that affects the women during 1-2 weeks before menstruation begins and disappears at the end of flow of menses. About 80% women with child bearing age have symptoms of PMS. And only small percentage of women for about 2-5% has significant premenstrual symptoms that are separate from the discomfort associated with menstruation.