No one knows precisely but there are several factors known to be implicated.
• Hormonal changes are a crucial feature of the menstrual cycle in all women. In the first two weeks of the cycle (i.e. the first two weeks after the start of a period) there is a substantial level of the hormone oestrogen and in the second two weeks the level of another reproductive hormone, progesterone, rises. These sex hormones affect not only a woman’s sex organs and her breasts but every organ of her body and an imbalance can produce a wide range of symptoms. Many experts now believe that low levels of progesterone are to blame for most, if not all, of the symptoms seen in PMT. Women with PMT have relatively lower levels of this hormone than do non-sufferers. It is the balance between oestrogen and progesterone in the blood that seems to be crucial. Oestrogen can antagonize progesterone so that even if you produce enough progesterone it can be wiped out by too much oestrogen. Normally progesterone acts as a natural diuretic, clearing fluid from the body. If a woman’s progesterone levels are low she accumulates salt and water, feels bloated, has joint pains, gains weight, feels tense, gets tired easily and can even have visual disturbances. A few women become so bloated, that they are unable to wear their contact lenses.
But the most important action of progesterone in this context is on sugar metabolism. Without enough progesterone the body is unable to deal with sugar properly and the result is hypoglycemia. It is this that produces so many of the mental symptoms seen in PMT. Hypo-glycaemic signs include headaches, migraines, fainting, weakness, irritability, aggressiveness and panic attacks. Once menstruation begins, sugar metabolism returns to normal and the woman feels well again. Alcohol and caffeine can also play havoc with blood-sugar levels and are best avoided pre-menstrually.
• Childbirth seems to increase the chances of suffering from PMT. The more babies a woman bears (especially if she has toxaemia) the more likely she is to suffer from PMT.
• Age. PMT generally increases with age. Women in their thirties seem to suffer most.
• Stress. This definitely seems to make PMT worse and even to precipitate it. Married women complain of more severe PMT than do single women, which may be accounted for by marital stress.
• Lack of physical activity seems to play a part too.
*8/72/5*
