DEAR DOCTOR K: I've always had infrequent periods, but I never thought much of it. My doctor recently used the word "anovulatory" to explain why I've had trouble getting pregnant. What does this mean? Could the two be connected?
DEAR READER: "Anovulation" means you are not ovulating -- releasing eggs. A woman's ovary should release approximately one egg each month. Once released, the egg travels into the fallopian tube. There, it can be fertilized by the entry of a sperm. The fertilized egg then enters the uterus.
When a woman does not ovulate, no egg is available to be fertilized by sperm. As a result, a woman cannot become pregnant. Women who are anovulatory have irregular, few or no periods.
What causes anovulation? Something wrong with the signals that cause ovulation. What are those signals? They start in a woman's brain. The brain has its own "calendar." It knows how old you are, and it knows what time of month it is. It knows the time of your life for you to start ovulating and the time to stop -- and it knows the time of the month for you to ovulate.
The brain controls ovulation and menstrual periods through a group of hormones, natural substances made in the brain that travel between different parts of the brain and also travel through the blood to the ovaries and uterus.
Anovulation can occur for many reasons. For example, women who exercise intensely, for long periods of time, may not ovulate. Women who are anorexic or have a very low body mass index may also have irregular or absent periods. In both cases, it appears that the brain hormones that normally stimulate ovulation are "dialed down," for reasons we don't understand.
Another common cause of irregular periods is polycystic ovary syndrome (PCOS). Women with PCOS don't ovulate normally. That's because the body doesn't respond normally to the hormone insulin.
Anovulation can also be a sign of abnormal hormone levels. Women who do not produce enough thyroid hormone may not ovulate normally. The same is true of women with high blood levels of prolactin. Prolactin is a hormone normally produced in the brain that stimulates the breast to produce milk during breastfeeding.
Once your doctor identifies the reason why you are not ovulating, the problem often can be corrected. For example, if you have PCOS, your doctor may prescribe medications that improve insulin sensitivity. This, in turn, may improve your chances of ovulating and becoming pregnant.
Even if your doctor cannot correct an underlying cause, you may still be able to become pregnant. A medication like clomiphene (Clomid), for example, can stimulate your ovaries to produce eggs.
Even if you do not want to become pregnant, it is important to recognize anovulation and to speak with your doctor about it. That's because anovulation can also affect other areas of a woman's health. Infrequent periods, for example, increase the risk of the bone-thinning disease osteoporosis. When talking to your doctor, ask what you can do to build and preserve bone strength.
Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.
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