Understanding Hormones Throughout Your Cycle

Hormones during menstrual cycle: learn how estrogen, progesterone, FSH, and LH shift throughout your cycle and why those changes affect how you feel every day.

If hormones throughout your cycle is what brought you here, If hormones during menstrual cycle is what brought you here, this guide can help you understand what may be happening. Most people learn the basics of the menstrual cycle at school: period, ovulation, repeat. What often gets skipped is the underlying hormonal story that actually drives everything. Those mid-cycle energy highs, the week of fatigue before your period, the way your skin changes throughout the month -- these are not random. They are the direct effects of four hormones doing exactly what they are supposed to do.

Learning to read your cycle through a hormonal lens is one of the most empowering things you can do for your wellbeing. It shifts the experience from confusing to understandable, and it helps you know when something is worth paying attention to.

Hormones throughout your cycle: Hormones during menstrual cycle: Website Blog

The Four Hormones That Run Your Cycle

Your cycle is controlled by what researchers call the hypothalamic-pituitary-ovarian (HPO) axis. Think of it as a communication loop: your brain sends hormonal signals to your ovaries, your ovaries respond, and feedback travels back up to the brain to regulate the next signal. The four main players in this system are:

Follicle-stimulating hormone (FSH). Produced by the pituitary gland at the base of your brain, FSH does exactly what its name suggests: it stimulates follicles inside your ovaries to grow and mature. Each follicle contains an egg. Rising FSH levels at the start of your cycle kick off the development of a small group of follicles, though usually only one will fully mature.

Luteinizing hormone (LH). Also released by the pituitary gland, LH is best known for triggering ovulation. A sharp surge in LH, typically lasting 24 to 36 hours, signals the most mature follicle to release its egg. LH levels rise abruptly around the middle of your cycle and then fall quickly once ovulation has occurred.

Estrogen. The term estrogen actually refers to a group of hormones; the one most active during reproductive years is estradiol. Estrogen is produced mainly by the developing follicles in your ovaries. It builds up the lining of your uterus (the endometrium), supports cervical mucus production, and has wide-ranging effects on mood, bone density, skin hydration, and energy levels. Estrogen peaks just before ovulation and has a smaller secondary rise in the luteal phase.

Progesterone. After ovulation, the follicle that released the egg transforms into a structure called the corpus luteum, which begins producing progesterone. This hormone stabilizes and thickens the uterine lining to support a potential pregnancy. Progesterone also has a calming, slightly sedating effect on the body. If no pregnancy occurs, the corpus luteum breaks down, progesterone drops sharply, and your period begins.

Your Cycle Phase by Phase

A typical cycle runs anywhere from 21 to 35 days, with most people falling somewhere in the middle. If yours varies in length, that is often completely normal. You can learn more about why cycle length shifts in this health library article on irregular cycles.

Here is what your hormones are doing during each phase:

During Your Period (Days 1 Through 5, Approximately)

Day 1 is officially the first day of your period. At this point, both estrogen and progesterone are at their lowest. The drop in progesterone is what caused your uterine lining to shed. FSH begins to climb gently during this phase, starting the process of stimulating new follicle growth for the cycle ahead.

Many people feel physically drained or emotionally flat during menstruation. That is a direct result of low hormone levels, particularly low estrogen. It is not a malfunction; it is simply where the hormonal curve sits at this moment in your cycle.

The Follicular Phase (Days 1 Through 13, Approximately)

The follicular phase technically begins on day 1 (overlapping with your period) and continues until ovulation. As FSH rises, a group of follicles starts growing inside your ovaries. These follicles produce estrogen, so estrogen climbs steadily throughout this phase.

Rising estrogen does a lot of things. It thickens the uterine lining in preparation for a potential pregnancy. It also stimulates the cervix to produce fluid that becomes progressively more slippery and clear as ovulation approaches, which many people recognize as a change in vaginal discharge. Beyond reproduction, rising estrogen tends to lift mood, sharpen focus, and increase physical energy. Many people feel their best in the late follicular phase, the week or so leading up to ovulation.

You can read a detailed breakdown of this phase in the follicular phase guide.

Ovulation (Around Day 14 in a 28-Day Cycle)

When estrogen peaks and crosses a threshold, it triggers the pituitary to release a large burst of LH. This LH surge causes the dominant follicle to rupture and release a mature egg. Ovulation itself usually happens 24 to 36 hours after the LH surge begins.

The egg travels down the fallopian tube toward the uterus, where it can be fertilized for roughly 12 to 24 hours. For a fuller picture of how ovulation works and how to recognize its signs, the ovulation explained article covers it in detail.

Some people notice a brief, sharp twinge of pelvic pain at ovulation (called mittelschmerz), a slight increase in libido, and a peak in cervical fluid that resembles raw egg white. These are all driven by the hormonal peak at this phase.

The Luteal Phase (Days 15 Through 28, Approximately)

After ovulation, the burst follicle becomes the corpus luteum and progesterone production begins. Progesterone is the dominant hormone of the luteal phase. It rises steadily over the first week after ovulation, with a secondary, smaller rise in estrogen alongside it.

Progesterone creates a thicker, more stable uterine lining. It also raises your resting body temperature slightly (by about 0.2 to 0.5 degrees Celsius), which is why basal body temperature tracking can confirm ovulation after the fact. The progesterone-to-estrogen ratio in this phase can affect how you feel emotionally and physically.

If no fertilized egg implants in the uterine lining, the corpus luteum starts to break down around a week after ovulation. Both progesterone and estrogen fall. In the final days before your period, this drop is what triggers premenstrual symptoms for many people: bloating, breast tenderness, mood shifts, disrupted sleep, and fatigue. The uterine lining then begins to shed, and day 1 of the next cycle begins.

The luteal phase guide goes deeper on why this phase matters so much for both health and fertility.

Why Hormone Fluctuations Show Up in Your Body

Hormones do not stay neatly inside the reproductive system. Estrogen and progesterone receptors exist throughout your body, including in your brain, skin, bones, gut, and cardiovascular system. That is why hormonal changes ripple outward in ways that feel personal and sometimes puzzling.

Energy and mood. Estrogen has a positive relationship with serotonin, the neurotransmitter associated with mood regulation. When estrogen is rising in the follicular phase, many people notice they feel more sociable, motivated, and emotionally resilient. When estrogen and progesterone both drop before a period, those serotonin-supporting effects fade, which can contribute to the low mood, irritability, or anxiety that some people experience in the late luteal phase.

Sleep. Progesterone has a mild sedating quality and can promote deeper sleep in the early luteal phase. But as both hormones drop in the days before your period, sleep quality often suffers. You may find it harder to fall or stay asleep in those final premenstrual days.

Skin. Estrogen supports collagen production and skin hydration. Many people notice their skin looks clearer and more luminous around ovulation, when estrogen is at its peak. In the luteal phase, rising androgens (male hormones that fluctuate subtly in women too) can increase oil production and contribute to pre-period breakouts.

Digestion. The gut has estrogen and progesterone receptors, and hormonal shifts can influence gut motility. Some people experience constipation in the luteal phase (when progesterone slows the gut) and looser stools or cramping at menstruation (partly driven by prostaglandins, which are released when the uterine lining sheds).

When Hormonal Shifts Feel Like More Than Normal Fluctuations

Some degree of hormonal variation is expected and healthy. But certain patterns are worth discussing with a healthcare provider:

• Premenstrual symptoms so severe they interfere with work, relationships, or daily life. This may point to premenstrual dysphoric disorder (PMDD), a condition linked to heightened sensitivity to the normal hormonal drop before menstruation.
• Very irregular or absent cycles. Missed periods or highly unpredictable cycle lengths can reflect hormonal imbalances involving FSH, LH, thyroid hormones, or androgens.
• Signs of significantly low estrogen, including hot flashes, vaginal dryness, or bone pain, outside of expected life stages.
• Heavy or prolonged periods that do not fit your normal pattern.

Flow & Glow can help you log symptoms alongside your cycle days, making it easier to spot patterns and bring meaningful information to a healthcare conversation when you need it.

Cycle tracking is a tool for self-knowledge, not self-diagnosis. If something feels off, a clinician can run hormone panels and interpret results in the context of your full health picture.

Written by Flow & Glow Editorial.

Reviewed by Dr. Jennifer Martinez, MD, FACOG.