Menstrual cycle hormones, phase by phase

Four hormones run the menstrual cycle: follicle-stimulating hormone (FSH), luteinizing hormone (LH), estrogen and progesterone. FSH and LH come from the pituitary gland, a small gland at the base of your brain. Estrogen and progesterone come from your ovaries, released in response to those pituitary signals.

The pituitary and ovaries work as a loop. FSH tells your ovaries to grow a follicle, the follicle makes estrogen, and estrogen tells the pituitary how much FSH and LH to send next. Progesterone joins the picture after ovulation, once the ruptured follicle turns into a short-lived gland called the corpus luteum.

This loop repeats roughly every 21 to 35 days, though the exact rhythm varies between people and sometimes between cycles for the same person. Each phase of your cycle (menstrual, follicular, ovulation, luteal) is named for what's happening to your uterine lining or ovary, but it's this hormone loop that drives all of it. For what happens physically in each one, see the 4 phases of the menstrual cycle.

Estrogen starts low during your period, then climbs through the follicular phase as a follicle matures. It peaks sharply just before ovulation, dips for a day or two, then rises again in the luteal phase alongside progesterone.

Progesterone stays near zero until after ovulation. Once the corpus luteum forms, progesterone rises steadily through the luteal phase, usually peaking about a week before your next period. If the egg isn't fertilized, the corpus luteum breaks down, and both estrogen and progesterone fall sharply in the two to three days before bleeding starts.

That fall is the trigger for your period itself, and for a lot of the physical and emotional symptoms many people notice in the days beforehand. The curve isn't a straight line, and it moves at different speeds for different people. You can see roughly where you are right now on the menstrual cycle hormone chart, or check what phase of your cycle you're in based on your last period.

FSH, as the name suggests, stimulates follicle growth. Early in your cycle, FSH rises and recruits a group of follicles in your ovary, each holding an egg. Usually one follicle becomes dominant and keeps growing while the rest stop developing.

LH stays low for most of the follicular phase, then surges sharply about 24 to 36 hours before ovulation. That surge, triggered by the peak in estrogen from the dominant follicle, is what causes the egg to be released. It's the same LH surge that ovulation predictor kits detect in urine.

After ovulation, both FSH and LH drop back down and stay low through the luteal phase, while progesterone takes over as the dominant hormone. If no pregnancy happens, falling progesterone lets FSH start climbing again near the end of the luteal phase, and the next cycle begins.

Estrogen and progesterone also cross into the brain, where they affect areas tied to mood, memory and threat response. Progesterone's breakdown product, allopregnanolone, works on some of the same brain receptors as certain anti-anxiety medications, which helps explain why its rise and fall in the luteal phase can shift how calm or on edge you feel.

A 2025 review proposed that people are sensitive to different hormonal events: some react to the surge in progesterone or estrogen right after ovulation with irritability, others react to the drop in estrogen before a period with low mood or fog [2]. Brain scans taken at different cycle phases also show the luteal phase changes how areas involved in working memory connect to each other, which may be part of why focus feels harder some weeks [3].

Anxiety symptoms often flare in the same premenstrual window, which the most consistent evidence ties to the underlying hormone shift [1]. PTSD symptoms also change across the cycle, though research on exactly when is less consistent [1]. Women not on hormonal birth control also report more day-to-day swings in agitation and energy than women on it, which points to the natural hormone cycle itself as a driver of some of that variability [4]. None of this means a bad mood before your period is only hormones. It means hormones are one real input, alongside whatever else is happening in your week.

Everyone's estrogen and progesterone move through roughly the same pattern each cycle. What differs from person to person is how sensitive the brain is to that pattern, not the hormone levels themselves. This is the core idea behind premenstrual dysphoric disorder (PMDD): research has found PMDD is a different brain response to normal hormone changes, not a result of abnormal hormone levels (Schmidt et al., 1998, NEJM; Dubey et al., 2017, Molecular Psychiatry).

PMDD affects about 1.6% of women and girls when confirmed with daily symptom tracking, and about 3.2% on a provisional diagnosis (Reilly et al., 2024, Journal of Affective Disorders). The diagnosis needs at least five symptoms, including a mood symptom such as irritability or low mood, in the week before a period, easing within a few days of it starting. Ordinary PMS can involve some of the same symptoms, just at a level that doesn't take over your week. Symptoms in each phase of your cycle breaks down what's typical and what's worth tracking day by day.

Tracking what you feel against where you are in your cycle usually shows whether a hormone pattern or something else is driving a bad week. Niyora is a PMS and PMDD support app that gives you an estimated PMS window and a place to write down your mood each day, so the pattern becomes easier to spot. How your menstrual cycle affects your mood and the luteal phase go deeper into what that tracking can look like.