Lesson 22 – Variations in Fertility Chart Patterns

Lesson Objectives:

  • Understand different variations in fertility chart patterns
  • Learn how interpretations of fertility chart patterns are made

Major Points in this Lesson:

  • Fertility charts may differ from the ideal. 
  • Visualize a variety of common, non-ideal chart patterns.
  • Some charts may be more difficult to interpret.

Fertility charts do not look the same for all women. In fact, it’s quite common to see significant variations in chart patterns from woman to woman. No matter how your chart differs from the “ideal,” it’s important to understand how to interpret your unique results. An in-ear thermometer is the best way to build an accurate chart. With data from your fertility chart, look for the following patterns:

Slow Rise

When reading your fertility chart, you may notice a rising pattern. The most common variation on a basal body temperature (BBT) chart pattern is the sloping rise. With a sloping rise pattern, there is an obvious thermal shift with temperatures rising in a curved pattern over a several day period before abruptly stopping. 

Another variation is the slow rise, which is similar to the sloping rise. In a slow rise pattern, a thermal shift is not obvious until several days past ovulation. Much like a sloping rise, temperatures increase gradually but in smaller increments over an extended period of time. The highest post-ovulation temperatures are reached after an average of four to six days.
Fallback Rise

Another common variation often seen in fertility charts is the fallback rise. Also known as a fallback thermal shift, this common variation is described as an obvious thermal shift that occurs immediately following ovulation. In a fallback rise pattern, the temperature rises significantly and abruptly before dropping immediately. It then rises again and remains unchanged throughout the luteal phase. 

It can sometimes be difficult to determine if you are in fact seeing a fallback rise pattern or if you’re simply seeing a one-time high temperature fluke. To determine if the pattern was indeed a fallback rise, turn to your non-temperature fertility signs, as well as your luteal phase length. 

Variations are highly common in fertility charts with no two women experiencing the same exact patterns from month to month. While your unique pattern may not be the “ideal” pattern, it can clue you in on your fertility status.