Although the exact cause of PMS has not been ascertained, several factors have been identified that influence the experience of the syndrome. It is thought that the primary cause of the various symptoms of PMS is hormonal imbalance that results from natural fluctuations in the menstrual cycle. Other factors can also contribute to PMS symptoms.

Hormonal Causes of PMS
The menstrual cycle is regulated by hormones such as estrogen and progesterone, among others. However, these hormones have other roles in the body aside from regulating menstruation and reproduction in general. In fact, estrogen and progesterone have effects on systems as diverse as the nervous, musculoskeletal, digestive, and cardiovascular systems; nearly every part of the body is influenced by these hormones in some way.

During the first half of the menstrual cycle, estrogen levels rise, which causes the uterus lining to thicken in preparation for a potential pregnancy. At about the midway point of the cycle, the levels of progesterone and other hormones increase to trigger the release of an egg and further prepare the uterus for a possible pregnancy. If the egg is not fertilized, then hormone levels drop, which causes the uterine lining to shed in what is known as a period. This natural drop in hormone levels is also associated with the symptoms of PMS.

Other, Less Common Causes of PMS
Other factors, like stress and nutrient deficiencies, can also cause or contribute to PMS.

It is not known why some women are more greatly affected by natural hormonal shifts in the menstrual cycle than others, though genes may be an influence.

Keep reading to learn about the different signs and symptoms associated with PMS.