The following are the FertilChart guidelines to interpret your charts:

  1. BBT charting is usually done to assess whether ovulation has already happened. You cannot usually determine ovulation reliably from looking at the curve unless it's at least 3 days after ovulation.
  2. You cannot predict ahead of time from looking at the chart if ovulation is going to happen in the future. You can only tell ovulation if it has already happened.
  3. The optimal time in your menstrual cycle to send your chart for evaluation is at the end of your menstrual cycle after your next period has come (Don't forget to indicate the completed cycle by placing the 'M' on the appropriate day at the cycle end).
  4. The next best time to send in your chart for an expert evaluation is about a week or so after presumed ovulation, when you think you can see the beginning of a biphasic chart. Sending us your chart for evaluation at these times allows for a better and more complete evaluation of your cycle.
  5. It's helpful to indicate at the end of your prior cycle that your menstrual period has come (an 'M' is seen in the 'Bleeding' row). This allows us to calculate the cycle length and the corpus luteum phase (time between ovulation and next menstrual period).
  6. We usually check your chart for ovulation and coverline. There is little we can say about your chart early in the cycle because ovulation is usually not reliably seen until much later on.
  7. A one-day or two-day change in temperature (up or down, dip or rise) is usually insignificant. The pattern of the chart is more important.
  8. Ovulation can only be reliably diagnosed when the temperature has stayed up for a minimum of three days (biphasic chart). Ovulation cannot be reliably diagnosed from a one- or two-day change in temperature. A dip does not reliably indicate that you ovulated. And a dip can never indicate ahead of time that ovulation is soon going to happen.
  9. If you start charting late in the menstrual cycle it's very difficult to assess the chart for ovulation.
  10. If you miss too many days, we can't reliably interpret the chart.
  11. Don't fill in a temperature on days where temperatures were not taken. Don't ever change a temperature if it did not fit the "ideal" curve just to make the curves look better and more complete. Pretending to have a temperature where there was none, plotting an inaccurate or non-existing temperature, or adjusting it to a "better" temperature does not help you and confuses us.
  12. You may have read somewhere else that it's OK to adjust a temperature under certain circumstances. We at BabyMed feel it's not OK to change or "adjust" a temperature. Adjusting temperatures is too inaccurate to make sense. It distorts your chart. If a temperature was taken incorrectly or not within the right time frame, we suggest that you keep track of it and write down that temperature and what happened. No matter if you like a temperature or you don't like a temperature. Please post your temperatures as you read them, and if necessary check off the valid box.