Figure 1.

Example cycle tracking history for the same user, demonstrating 2 scenarios: in which they track all of their periods (top) and in which they skip tracking of 1 of their periods (bottom). Cycle start dates are highlighted in green and the skipped period tracking is highlighted in red. The bottom panel showcases how skipping tracking of 1 period can result in inflated observed cycle lengths—instead of 2 subsequent cycles of lengths 27 and 35, respectively, because the user skips tracking of a period, it appears that they have 1 cycle of length 62. This is because cycle length is determined by the number of days between tracked periods. This phenomenon holds analogously if a user skipped more than 1 period (in which case 3 subsequent cycle lengths would appear as if it were a single, inflated cycle length).