At a glance
- The secretory phase runs from ovulation to your period, about 12 to 14 days, and is the uterine side of what doctors call the luteal phase.
- Progesterone and allopregnanolone rise then fall during this phase, and that drop can trigger PMS and PMDD symptoms.
- PMDD symptoms cluster in the final week of this phase and ease within a few days of your period starting.
- Guessing which phase you're in from symptoms or dates alone is unreliable; daily tracking across two cycles is the standard used to confirm PMDD.
- Niyora's Moon feature can help you work through a hard moment during this phase before you respond to anyone.
What is the secretory phase?
The secretory phase is the second half of the uterine cycle. It starts right after ovulation and ends when your period begins, usually lasting about 12 to 14 days.
During this phase, three things happen in order:
- The ruptured follicle becomes the corpus luteum, a temporary structure that makes progesterone and some estrogen.
- Progesterone thickens the uterine lining so it can support a pregnancy if the egg is fertilized.
- If pregnancy doesn't happen, the corpus luteum breaks down, and progesterone and estrogen fall sharply in the days before your period.
Doctors sometimes call this same stretch the luteal phase. 'Secretory' describes what the uterine lining is doing. 'Luteal' describes what the ovary is doing. They overlap almost exactly.
Read more in the luteal phase: what's happening in your body and mood and Corpus Luteum: what it means.
How does the secretory phase relate to PMS and PMDD?
PMS and PMDD both show up during the secretory phase, in the one to two weeks before your period starts.
As progesterone rises in this phase, your brain also makes allopregnanolone, a byproduct of progesterone that normally has a calming effect. Most people adjust to that shift without much trouble. People with PMDD seem to react differently to the same hormone changes, not to abnormal hormone levels.
PMDD is a diagnosis in the DSM-5-TR and ICD-11. It requires:
- At least five symptoms, including one mood symptom (mood swings, irritability, low mood or anxiety)
- Symptoms confined to the final week of the secretory phase, before your period
- Symptoms that ease within a few days of bleeding starting, and are minimal the week after
See PMDD (premenstrual dysphoric disorder), explained and What causes PMDD? for the full picture.
What does the research say about the secretory phase?
Researchers studying this phase have found a few consistent patterns, though measuring it precisely is harder than it sounds.
Cortisol, the main stress hormone, tends to be lower in the luteal (secretory) phase than in the follicular phase before it, by a small but measurable amount across a pooled analysis of 778 women (Hedges' g of 0.13) (1). Some scientists think this tracks with allopregnanolone, which moves in the opposite direction across the cycle.
A trial in women with PMDD found that blocking the enzyme that converts progesterone into allopregnanolone eased core mood symptoms at a higher dose, supporting allopregnanolone's role in this phase (3).
Working out exactly which phase someone is in isn't always straightforward:
| Method | How it works | How reliable |
|---|---|---|
| Counting days from your last period | Estimates phase from calendar days alone | Error-prone; often disagrees with hormone-based methods (2) |
| Hormone level ranges | Uses typical ranges to guess phase | Only fair to moderate agreement with other methods (2) |
| Limited hormone measurements | Infers phase from one or two blood draws | Can miss shifts between days (2) |
That's part of why PMDD is confirmed with daily symptom ratings across at least two cycles, not a single guess at timing.
Why does this matter, and what related terms should you know?
Knowing you're in the secretory phase can change what you do next.
Because PMDD symptoms cluster in this window, some treatments are timed to it. Guidelines note that SSRIs can work when taken only during the luteal phase rather than every day, though a doctor decides what's right for you.
Niyora is a PMS and PMDD support app. If you want somewhere to put a hard conversation until the wave passes, its Moon feature lets you write what happened, see it from another angle, and draft a reply you can hold for 20 minutes.
A few related terms worth knowing:
- Allopregnanolone: what it means, the hormone byproduct behind a lot of this phase's mood effects
- PMS and PMDD research, summarised, for the studies behind these terms
Questions people ask
Is the secretory phase the same as the luteal phase?+
The secretory phase and the luteal phase describe the same two weeks, just from different angles. The secretory phase describes what the uterine lining is doing (thickening). The luteal phase describes what the ovary is doing (making progesterone through the corpus luteum). They start and end at the same points in your cycle.
How long does the secretory phase last?+
The secretory phase usually lasts about 12 to 14 days, running from ovulation until your period starts. Its length can vary slightly from cycle to cycle and person to person. If this phase stretches past two weeks regularly, or your periods are very irregular, tell a doctor.
Does the secretory phase cause PMS and PMDD?+
The secretory phase is when PMS and PMDD symptoms typically appear. Progesterone and allopregnanolone rise then fall during this phase, and some brains react to that shift with irritability, low mood or anxiety. The hormone changes are normal; the reaction varies by person.
Why do some people feel fine in the secretory phase and others don't?+
Hormone levels during the secretory phase look similar across most people who have PMDD and those who don't. Research points to differences in how the brain responds to the rise and fall of allopregnanolone, a progesterone byproduct, rather than to abnormal hormone amounts. That sensitivity is still being studied today.
What happens if there's no pregnancy at the end of the secretory phase?+
If there's no pregnancy, the corpus luteum breaks down at the end of the secretory phase. Progesterone and estrogen drop sharply, which triggers the uterine lining to shed as your period. That hormone drop is also linked to PMS and PMDD symptoms easing once bleeding starts.
Sources
- 1.Higher Circulating Cortisol in the Follicular vs. Luteal Phase of the Menstrual Cycle: A Meta-Analysis, Frontiers in endocrinology, 2020
- 2.Determining menstrual cycle phase: An empirical examination of methodologies and recommendations for improvement in behavioral and brain sciences, Hormones and behavior, 2023
- 3.5α-Reductase Inhibition Prevents the Luteal Phase Increase in Plasma Allopregnanolone Levels and Mitigates Symptoms in Women with Premenstrual Dysphoric Disorder, Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 2016