My cycles can be irregular. I've had cycles as short as 17 days as as long as 69. I'm having a pretty long cycle right now (55 and counting), and ovulated very late. I know this because my CM and BBT indicate it and another app detected it. However, Glow has been suggesting my period is coming up for a few days now, even though it's been only 4-6 days after ovulation. I have to keep pushing it back. It's seems Glow isn't taking the late ovulation into consideration, and I don't feel like I can trust its predictions. Maybe Glow should have an option in the account settins for people with irregular cycles, or should be able to detect them and recalculate dates.