Cycles that are consistently longer than 35 days or shorter than 21 days. Amenorrhea: The complete absence of menstrual periods. Tracking Deviations:

Difficulty getting a positive result on ovulation predictor kits. Primary Causes Polycystic ovary syndrome - World Health Organization (WHO)

Absence of the typical slight temperature rise (0.5 to 1.0°F) after mid-cycle.