Demystifying the Menstrual Cycle

Menstrual Cycle 101: It’s More Than Just Your Period

A menstrual cycle is the 28–35 day hormonal rhythm your body follows to prepare for a possible pregnancy.¹ But reproduction isn’t even half of the story here. It’s a full-body hormonal dance that affects your brain, metabolism, and mood. Per Dr. King MD, FACOG, “a menstrual cycle is not just a menstrual period.”

Here’s what’s really happening behind the scenes:

1. Menstrual Phase (POV: You Get Your period)

This is the part most people know all too well—it’s your uterus shedding its lining because the pregnancy it spent all that time prepping for, didn’t happen. Think of it as your uterus going on protest because its organization rejected their growth proposal. During this time, estrogen and progesterone levels are low, which can explain why you might feel a little tired, emotional, or crampy.²

2. Follicular Phase (Prep Mode: Pre-Ovulation)

This phase starts on the first day of your period and continues until ovulation. Your brain releases follicle-stimulating hormone (FSH), nudging your ovaries to grow follicles (tiny sacs that each contain an egg). During this time, estrogen begins to rise, boosting your mood and energy. Let’s just set the record straight here. If follicular phase you feels like a completely different person than luteal phase you: no, you’re not crazy and yes there IS a biological reason as to why. Many people feel clearer, more focused, energetic, physically strong, and even more social during this time.^{2, 7}

So if your body’s telling you to book that trip, take that workout class, or hit that party, it very well may be time to listen.

P.S. :

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3. Ovulation Phase (The Big Release)

Around day 14, luteinizing hormone (LH) spikes, causing your ovary to release an egg. This is what’s known as your “fertile window.” Estrogen peaks, and you might feel more confident—maybe even a touch sexier. Some experience a little pelvic twinge during ovulation; it’s called mittelschmerz, and it’s totally normal (just lean in and do your thing).³

4. Luteal Phase (PMS Territory)

After that feel-good ovulation period, your body ramps up progesterone to prep the uterus in case the egg gets fertilized. If it doesn’t, both estrogen and progesterone levels drop. That hormonal drop-off can cause bloating, fatigue, and cravings—classic PMS, as we know it. That sudden pang for waffle fries or warm chocolate chip cookies that comes right around the second half of your cycle? It’s real. Estrogen tends to suppress appetite, while progesterone can increase it.⁵ So, get the cookie. It’s science.

This can also explain any unforeseen mood swings; and any subsequent swings you may try & take back at that mood. Absolutely no judgement here. You may even feel a bit down or anxious during this phase. For some, this can feel mild. For others, it’s disruptive or even debilitating in the case of PMDD—aka Premenstrual Dysphoric Disorder, which can feel like PMS turned way up to 100.⁴

Life Stages of the Menstrual Cycle: What Changes Over Time

Menarche: D Day. Your First Period

Every woman in your life has a story about this. We all remember where we were, what our moms said to us, what we felt, how old we were. The confusion, excitement, maybe even the twinge of embarrassment that came with it all. It’s a major milestone that often marks the beginning of a lifelong relationship with your body.

Your 20s–30s: The Reproductive Years

Now this is typically when things settle into a more regular rhythm. Those hormones really start dancin’. Most cycles last between 21 and 35 days.⁸ But of course, things like stress, travel, intense exercise, or conditions (like PCOS or thyroid issues) can throw things off now and then.^{9 10} If your cycle is suddenly off, it’s worth paying attention to—it can be a silent signal from your body that something is up.

Pregnancy + Postpartum: Baby Steps Era

Your period takes a backseat during pregnancy, disappearing entirely. After giving birth, it may take weeks—or even months—to return, especially if you’re breastfeeding.¹¹ When it does come back, your cycle might not look the same. It could be heavier, lighter, more painful, or unpredictable. It’s totally normal—your hormones are just doing a little recalibrating.

Perimenopause + Menopause: The Age of Enlightenment

In your 40s or even late 30s, you may enter perimenopause—the transitional years leading up to menopause. A sort of preparatory time, if you will. Hormones start fluctuating wildly, causing irregular periods, night sweats, and mood changes—all while you’re still getting your period.

Menopause officially starts after 12 months without a period, usually around age 51.⁶ After that, estrogen levels stay low, which can impact bone health, heart health, and even memory. But remember, menopause isn’t an ending—it’s a transition into a new era of you. A tampon, cycle-syncing, period underwear-free era of you. Notice how much we’re repeating the word free here.