"Some months my period is nothing more than spotting and other months the flow is so heavy I'm changing the pad twice as much as usual.  What causes this?"

First always consult with your health care professional about changes in your periods.  You don't want to miss something serious.

If all other causes for this irregular bleeding is ruled out then it is probably due to perimenopause.  One of the first signals that perimenopause has arrived is a change in the period.  The flow can be lighter, darker, longer, or even shorter.

Let's take this question in two parts:

Number one: intermittent spotting and bleeding.  Spotting is defined as an unusually light menstrual flow. This is caused by irregular shedding of the uterine lining.  Little bits and pieces break away (bleeding), the body tries to repair the lining ( bleeding stops) and then sheds again.  This type of bleeding often signals little or no progesterone production. According to the book Midlife, Madness, or Menopause, spotting may happen a couple of days before your period would normally show up.  Often it's the result of anovulation- a cycle in which your ovaries did not release an egg ( no ovulation).  This is very common during perimenopause and as a woman gets closer to the actual menopause it may happen even more frequently.  If the spotting occurs after menopause then it could be a sign of a bigger problem and must be reported to a doctor. 

Another consideration about spotting during perimenopause and menopause involves the bones.  Studies have indicated that women of reproductive age who don't ovulate for a prolonged period of time may experience the same bone loss as a postmenopausal woman.  In a nutshell, intermittent bleeding and spotting can be caused by lack of ovulation (little to no progesterone production) and therefore excess estrogen

Heavy bleeding is also caused
by a hormonal imbalance.

For some women the slowing down of the ovaries during perimenopause and menopause may result in an excess of estrogen because of too little or no progesterone.  Lack of ovulation, a big sign that the ovaries are slowing down, and production of unopposed estrogen can cause the uterine lining to really build up.

According to Dr. Judith Reichman, in her book I'm Too Young to Get Old, when the uterine lining finally breaks down ( a period) the bleeding can be very heavy.  Because the shedding is uneven and some areas breakdown before others, the bleeding is prolonged.  This type of bleeding also involves clots and the blood may appear dark.  In a nutshell, this can be caused by the absence of ovulation (little to no progesterone production) and because of no ovulation the presence of excess estrogen.

Meet the Author
"Menopause Made Easy"
by Dr. Carolle Jean-Marat, MD
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Today's woman must educate herself about menopause and the risks and rewards of taking HRT, nutritional supplements, and homeopathic therapies. With humor, candor, and plain non-technical language, Dr. Jean-Murat discusses the current needs and concerns of midlife women, empowering us to make the right decisions. In our interview, she discusses Selecting over the counter products, Black Cohosh, and Racial Differences & Menopause and also features a FREE excerpt from her book, Stress and Depression. If you have any questions, you can ask them on our HotFlash support group.