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Temperature Shift Rule

If until the evening (6:00 pm) of the third consecutive day your temperature remains above the coverline, you can assume infertility.

If one temperature is higher than the six preceding temperatures it indicates the temperature shift. When using 'FAM / NFP,' a horizontal line, the coverline, is drawn above this temperature, when using 'NFP (AG NFP)' the coverline will be drawn through this temperature.
Lily will show infertility starting on day four to cover the timespan between 6:00 pm of day three and 12:00 am of day four.

Exceptions for FAM / NFP

  • Exception 1: If one of the following two temperatures falls on or below the coverline you have to wait on a third temperature that fits the rules.
  • Exception 2: If the third temperature lies below the required minimum you have to wait for one more temperature. This one has to be above the coverline, no matter how high, as long as it lies above it.

Exceptions for NFP (AG NFP)

  • Exception 1: If none of the three temperatures rise high enough above the coverline, you have to wait on a fourth temperature, which needs to be higher than the minimum.
  • Exception 2: If within these three days one of the temperatures drops on or below the coverline, the temperature shift rule has to be applied all over again, starting from the day it rises back above the coverline.

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