I’m using my phone’s ovulation tracking app. Isn’t that enough to identify my fertile period?

Most cycle-tracking apps predict ovulation based on a one-size-fits-all model — it’s commonly thought that ovulation happens on day 14 of a standard 28 day-cycle.

However, for majority of people with ovaries, that’s not the case³. In fact, one study found that the probability of correctly identifying a woman's ovulation day using cycle-tracking apps was as low as 21%¹.