Before I went on the pill several years ago, I had light periods with no cramping maybe twice per year. I also used to exercise at least two hours daily. I am now about 10 pounds heavier and only exercise one hour per day. After going off the pill last summer, I have had what seems like regular periods -- 32-35 day cycles, with heavy flow, cramping and the whole works. I figured I am now ovulating. We are trying to get pregnant, so I'm taking my basal body temperature. I have noticed some spikes, but not huge spikes. When I told this to my doctor, she said simply, "You are not ovulating." Does the lack of spikes alone indicate I am not ovulating, even with regular periods? If so, how come I am having periods?

C.B.

Your level exercise in the past may well have had something to do with your irregular periods at that time. Irregular menses and exercise often go hand in hand. The more you exercise, the greater the likelihood of menstrual or ovulatory problems. Aerobic exercise is the culprit here, while weight training may have less of an effect. Other factors include your age (the younger you are the greater the effect), the intensity and duration of exercise, the rate at which you increase your training schedule (those who rapidly build up miles/hours per week are more likely to see fertility problems), your diet (low-fat vegetarian diets may contribute), your weight and body fat (low weight and low body fat are associated with diminished ovarian function), and stress.

The basal body temperature (BBT) chart is used to track ovulatory function. A rise of about 1/2 degree seen midcycle typically indicates that ovulation has occurred. It impossible to predict before the fact when ovulation will occur, and even after the fact, the BBT chart is not really a good indicator of when ovulation occurred. It is a stab in the dark at best. In one study, researchers showed a number of BBT charts to a group of well-trained physicians. Unfortunately, the doctors rarely agreed on the day of ovulation and even whether the women actually ovulated. So I would not be too concerned by the lack of BBT chart evidence of ovulation, or your physician's interpretation of your chart.

There are better ways to check for ovulation. By checking your progesterone level on or about Day 24 or 25 of your cycle, your physician can unequivocally determine whether you are ovulating.

It's true, though, that some women do not ovulate but have regular menses. Why this happens is not entirely clear, and there are many plausible explanations. Prolonged estrogen stimulation of the uterine lining can result in an unstable endometrium that is prone to periodic bleeding. While this would seem to be the most likely cause for regular anovulatory bleeding, I would not worry about why the bleeding occurs regularly. I would focus your energy and resources on evaluating whether you are ovulating and, if not, developing a plan that will help restore normal ovulation and fertility potential.