Premenstrual Syndrome - Introduction

Introduction

Premenstrual Syndrome

Premenstrual syndrome (PMS) is a set of emotional and physical 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.

A menstrual cycle usually lasts an average of 28 days, although the cycle length may range from 21 – 34 days and still be considered normal. When a woman reaches her 40s the cycle lengthens, reaching an average of 31 days by age 49.

Ovulation occurs mid-way through the menstrual cycle, around day 14 (in a 28-day cycle). A menstrual cycle has two main phases, which precede and follow ovulation:

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• The follicular (proliferative) phase, which occurs from days 1 (when menstrual bleeding starts) through day 13.
• The luteal (secretory) phase, which occurs from days 15 - 28.

PMS is associated with the luteal phase of the menstrual cycle. Estrogen and progesterone levels rise in the first part of the luteal phase to help prepare the endometrial lining of the uterus for an embryo. If conception (pregnancy) does not occur, the levels of these hormones decrease in the latter part of the luteal phase, and the lining is shed through menstruation in the beginning of the follicular phase. Levels of other types of hormones also rise and fall during the menstrual cycle. [For more information, see In-Depth Report #100: Menstrual disorders.]

Premenstrual Dysphoric Dysorder

Premenstrual dysphoric disorder (PMDD) is a condition marked by severe depression symptoms, irritability, and tension before menstruation. The symptoms of PMDD are similar to those of PMS, but they are generally more severe and debilitating. Like PMS,symptoms of PMDD occur during the luteal phase in the week before menstrual bleeding begins. Symptoms usually improve within a few days after the period starts.

Click the icon to see an animation about the menstrual cycle.

Review Date: 07/26/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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