I am 28 and have three children. I have had regular periods, to the day, for three years. Now I am 12 days late and counting. I took a pregnancy test, and it was negative. What else can cause a late period?

W.

There are many possibilities for explaining a missed period; in your age group, pregnancy would certainly be high on the list. Stress is another possibility -- by interfering with the normal hormonal signals, stress can block ovulation and cause cycles to become irregular. Thyroid problems, again by interfering with the normal hormonal pathways, also can lead to a late period. Being overweight or underweight can also interfere with the normal menstrual cycle. If you are on birth control pills or DepoProvera, the medication itself may make periods disappear -- it is OK to not have periods on these medications, but it is not OK to not have periods on your own. Premature menopause is a very remote possibility.

If your period does not arrive within a couple of weeks, repeat the pregnancy test and make an appointment with your gynecologist. Usually after a discussion of your medical history, a physical exam and perhaps a couple of blood tests, the reason for missed periods can be identified and corrected.