Definition of Premenstrual syndrome:

Premenstrual syndrome (PMS) refers to a wide range of physical or emotional symptoms that typically occur about 5 to 11 days before a woman starts her monthly menstrual cycle. The symptoms usually stop when menstruation begins, or shortly thereafter.

See also: Premenstrual dysphoric disorder (PMDD)

Causes, incidence, and risk factors:

The exact cause of PMS has not been identified. Changes in brain hormone levels may play a role, but this has not been proven. Women with premenstrual syndrome may also respond differently to these hormones.

PMS may be related to social, cultural, biological, and psychological factors.

The condition is estimated to affect up to 75% of women during their childbearing years.

It occurs more often in women:

• Between their late 20s and early 40s
• Who have at least one child
• With a personal or family history of major depression
• With a history of postpartum depression or an affective mood disorder

The symptoms typically get worse in a woman's late 30s and 40s as she approaches the transition to menopause.

As many as 50% - 60% of women with severe PMS have a psychiatric disorder (premenstrual dysphoric disorder).