Written by
Louise W Lu, PhD, MPH, BMLS
Reviewed by
Michelle Ordner, Registered Nurse
Yvonne, 42. She eats clean, exercises regularly, and keeps sugar and alcohol low—she’s always believed she managed her health well. But lately, she’s noticed her body starting to feel… unfamiliar.
- Her pants feel tighter even though her weight hasn’t changed;
- She keeps waking up at 3 a.m.;
- Small things can suddenly make her irritable;
- Her once-thick hair is gradually thinning;
- Her menstrual cycle is becoming less predictable than before.
She started to question herself:
“Is it stress? Or am I really getting older? Could this be menopause?”
Many women notice these shifts in their late 30s to early 40s—sometimes as early as 35—as the body’s rhythm begins to change.
If you’ve recently felt that your body and emotions are “not quite the same,” but you can’t explain why—
Then this series will help you understand what perimenopause really is, why it happens, and how you can take better care of yourself through it.
What Is Perimenopause? The Full Journey From Regular Periods to Postmenopause
Perimenopause is the transitional phase when a woman gradually moves from a regular menstrual cycle toward menopause. It’s not that you “enter menopause” overnight—rather, it’s a period in which hormones slowly become less predictable and periods gradually become more irregular. The clearest way to understand this journey is to break it into six stages: a regular menstrual cycle, early perimenopause, mid perimenopause, late perimenopause, menopause (defined as 12 consecutive months without a period), and postmenopause.
These six stages don’t “switch” suddenly—they’re part of a continuous physiological process. You don’t need to label yourself precisely, but understanding the symptoms and blood-test trends in each stage can help you roughly identify where you are along the journey.
① Regular Menstrual Cycle: A Phase of Stable Hormonal Rhythm
Most women between ages 20–35 experience consistent ovulation and a stable hormonal rhythm. During this time, cycles are regular, sleep is usually good, and mood is relatively steady—often considered a “golden phase” of hormonal function.
Common signs / experiences in this stage
- Stable cycle length (often within 26–32 days)
- Steady mood, with only mild premenstrual discomfort
- Weight is easier to maintain; fat tends to distribute more around hips and thighs
- Thicker hair and better skin elasticity
- Deeper sleep with fewer awakenings
Typical blood-test trends
- FSH (follicle-stimulating hormone): generally lower and steady; good ovarian responsiveness
- LH (luteinizing hormone): a clear surge around ovulation
- Estradiol (E2): rises steadily before ovulation and peaks around ovulation
- Progesterone (also called P): rises significantly after ovulation, indicating a healthy luteal phase
- AMH (anti-Müllerian hormone): within the normal range for age, reflecting adequate ovarian reserve
- Ferritin, TSH, vitamin D: often within normal ranges
② Early Perimenopause: Ovulation Starts to “Occasionally Go Missing”
This commonly occurs between ages 35–45. From the outside, your cycle may still look regular, but ovulation may no longer happen every month. Estradiol fluctuations become more pronounced, while progesterone can be clearly insufficient in anovulatory cycles.
Noticeable signs / experiences
- Worsening PMS (premenstrual symptoms): bigger mood swings, breast tenderness, premenstrual anxiety
- Lighter, more fragile sleep—especially insomnia or restlessness before a period
- Small changes in flow and number of bleeding days
- Lower resilience—late nights feel harder to “recover” from
- More palpitations or migraines (often linked to higher estrogen variability)
Blood-test trends
- FSH: the average baseline rises slightly vs. younger years—your brain is “pushing” the ovaries harder
- Estradiol (E2): higher peaks followed by sharp drops; more obvious fluctuations
- Progesterone (P): lower in some cycles because some cycles do not ovulate
- LH: the surge becomes less consistent
- AMH: declines faster, signaling reduced ovarian reserve
- Ferritin may drop (especially if bleeding increases)
③ Mid Perimenopause: The “Hormone Roller Coaster” Stage
This is often the most obvious—and most confusing—phase. Estradiol can swing high and low, FSH keeps rising, and progesterone tends to remain low long-term. Your period pattern, mood, sleep, and weight may all become harder to predict.
Noticeable signs / experiences
- Irregular cycles: earlier or later than expected; varying lengths
- Flow becomes unpredictable—heavier or lighter—plus unstable bleeding duration
- Waking at night (2–4 a.m.), sometimes with night sweats or sudden heat
- Stronger mood swings: irritability, tearfulness, heightened sensitivity
- More abdominal fat—even without diet changes, “belly weight” is easier to gain
- Hair becomes finer and thinner; increased shedding
- Brain fog, reduced focus, weaker short-term memory
- Stronger cravings for sugar/carbs; more post-meal sleepiness
Blood-test trends
- FSH: often high most of the time, with large fluctuations
- Estradiol (E2): a “roller-coaster” pattern—sharp highs and lows
- Progesterone (P): persistently low; many cycles are anovulatory
- LH: the surge may be unclear or hard to capture
- AMH: noticeably lower or near the lower limit
- Fasting insulin and triglycerides: may rise in some people, suggesting metabolic stress
- Ferritin may decline (due to irregular bleeding patterns)
④ Late Perimenopause: Longer Gaps Between Periods as the Ovaries Near “Clocking Out”
Period intervals lengthen more clearly—40 days, 60 days, or even once every few months. Ovulation becomes very infrequent. Estradiol trends lower overall, though small “residual” fluctuations can still occur.
Noticeable signs / experiences
- Significantly longer spacing between periods
- Lighter bleeding, sometimes only spotting
- Frequent hot flashes and night sweats
- Vaginal dryness and lower libido
- Drier, thinner skin and reduced collagen
- Fatigue, joint stiffness, slower recovery
Blood-test trends
- FSH: elevated most of the time, approaching a menopausal pattern
- Estradiol (E2): generally lower, but may still fluctuate within a smaller range
- Progesterone (P): extremely low long-term; ovulation is rare
- LH: higher but without a clear ovulatory surge
- AMH: very low or undetectable
- Vitamin D and serum calcium: more likely to run low (higher bone-loss risk)
⑤ Menopause: The Day You Reach 12 Consecutive Months Without a Period
Menopause is not a stage—it’s a point in time defined as 12 months since your final menstrual period. Hormones shift from dramatic swings to “low but more stable.” Some symptoms ease, while others may persist.
Noticeable signs / experiences
- No periods for ≥ 12 months
- Hot flashes may continue but often less intense than peak perimenopause
- Sleep may improve slightly, but awakenings can still happen
- Vaginal dryness and discomfort with sex are common
- Abdominal fat proportion may continue to increase
Blood-test trends
- FSH: high and relatively stable—typical menopausal pattern
- Estradiol (E2): drops to menopausal range with less fluctuation
- Progesterone (P): close to zero
- LH: similar to FSH, settling into a postmenopausal pattern
- Blood lipids (LDL, triglycerides): more likely to rise
- Higher risk of elevated fasting insulin (slower metabolism)
⑥ Postmenopause: A New Long-Term Stable Phase
Postmenopause begins after menopause and continues for the rest of life. Hormones stay at low levels and no longer fluctuate. Your physiology becomes more stable, while bone, cardiovascular, and metabolic health become the new key priorities.
Noticeable signs / experiences
- Bone density declines year by year (without intervention)
- Skin becomes drier, thinner, and looser
- Joint stiffness and aches
- Increased cardiovascular risk
- Vaginal dryness may persist
- Sleep becomes more fragile but steadier (less driven by hormonal swings)
Blood-test trends
- FSH: remains high and stable
- Estradiol (E2) and progesterone (P): low and stable
- LH: stable postmenopausal pattern
- Vitamin D is often low
- Blood lipids tend to rise more easily
- Fasting glucose and insulin become more sensitive indicators of metabolic health
- DXA bone density scans often show osteopenia or an osteoporosis trend
What You’re Experiencing Is a Journey of Your Body Recalibrating
Perimenopause isn’t something you simply need to “endure”—it’s a natural process in which your body is resetting its rhythm. Once you understand the differences across the six stages, and how hormones behind the scenes can affect your mood, sleep, weight, and metabolism, you’ll be able to see more clearly: these changes aren’t because you did anything wrong—they’re your body telling you it needs a new kind of support.
Every woman enters perimenopause at a different time, and symptoms can look very different from person to person. But you don’t have to figure it out alone—when you can recognize your body’s signals and use the right tools, you can absolutely move through this journey with strength, steadiness, and clarity.
- The 10 most common perimenopause symptoms (and how to tell them apart)
- How to use blood tests to estimate which stage you may be in
- Which nutrients, lifestyle strategies, and supplements can truly support you
- Which symptoms may call for further medical evaluation
Your body is entering a new chapter—and you have the ability to understand it, support it, and take the lead.
We’ll walk with you every step of the way.
Authors:
Michelle Ordner
Registered Nurse (RN)
Michelle's expertise spans healthcare, nutrition infusion, and menopausal care. She began her nursing career in New Zealand in 1991 and has since served 17 years in critical care across the USA. After returning to NZ, she trained in cosmetic medicine and stem cell therapy, and holds a UK certification in intravenous nutrition. Her work focuses on integrative care for menopausal health and wellness.
