Blog / What even is the luteal phase?
The part of the cycle that gets the least explanation and causes the most confusion.
If you've ever felt completely fine one week and then inexplicably raw the next — more tired, more irritable, crying at a dog food commercial — there's a real hormonal reason, and it has a name: the luteal phase.
Once an egg is released, the follicle that held it turns into something called the corpus luteum, which pumps out progesterone for roughly the next two weeks. Estrogen, which had been climbing toward ovulation, drops. Both hormones then fall sharply right before your period starts — and that drop is what triggers a period in the first place.
That hormonal swing is also why the luteal phase is when PMS symptoms show up, and for some people, something more specific: PMDD.
A single bad week doesn't mean much on its own. A pattern that repeats, luteal phase after luteal phase, is actually diagnostically meaningful — it's the difference between "I was just having a rough week" and a real, trackable hormonal pattern.