A phrase that started as a joke and stopped being funny
"Second puberty" showed up on TikTok and Instagram sometime in early 2025 as a self-deprecating punchline — women in their late thirties posting about sudden acne along the jawline, hair that wouldn't hold a style anymore, and a temper that flared over things that never used to register. By the summer of 2026 the hashtag had stopped being a joke and started functioning as shorthand for something millions of women were experiencing without a name for it: perimenopause arriving five, sometimes ten years earlier than the cultural script had prepared them for.
The term is not clinical, and no medical body has adopted it. But the symptom cluster it describes is real, and it's arriving on a schedule that catches most women off guard. Perimenopause — the hormonal transition leading up to menopause — can begin in a woman's mid-to-late thirties, even though the average age of menopause itself sits at 51 in both the US and UK. That gap, sometimes a full decade, is where "second puberty" lives: skin, sleep, mood, and metabolism all shifting while a woman is still telling her doctor she's "too young for that."
Why the medical system is behind the trend, not ahead of it
Here's the uncomfortable part. A JAMA-published survey of US obstetrics and gynecology residency programs found that fewer than a third required any formal menopause-specific training, leaving many newly certified OB-GYNs without structured education on a transition that half their future patients will go through. Women showing up with brain fog, joint pain, or irregular cycles in their late thirties frequently get tested for thyroid issues, anxiety, or depression — all reasonable things to rule out — while perimenopause itself doesn't make it onto the list until symptoms have been dismissed two or three times.
Mary Claire Haver's 2024 book The New Menopause spent months on bestseller lists partly because it gave language to a gap plenty of women had already noticed themselves: their mothers didn't talk about this, their doctors weren't trained on it, and the information they could find online ranged from solid science to supplement marketing dressed up as medical advice. In the UK, Davina McCall's documentaries and advocacy work pushed the conversation further into the mainstream, and NICE's guideline NG23 — last meaningfully updated in 2015 — remains the reference point GPs are supposed to work from, even as patient advocacy groups argue it hasn't kept pace with how early and how variably perimenopause actually presents.
What's actually changing, and why it doesn't feel like "just hormones"
Estrogen and progesterone don't decline in perimenopause so much as swing unpredictably, some cycles running hormone-rich and others crashing low, which is a large part of why symptoms feel erratic rather than steady. One month brings a normal cycle and clear skin; the next brings a period ten days late, cystic breakouts along the jaw, and a two a.m. wake-up that has nothing to do with stress. Collagen production also drops sharply as estrogen becomes less consistent, and dermatologists now cite this as one reason skincare routines that worked reliably for fifteen years suddenly stop delivering the same results.
Weight redistribution is another piece nobody warns you about in advance — not necessarily weight gain, but fat shifting toward the midsection even when diet and exercise haven't changed. This is driven by the same hormonal volatility, and no amount of willpower reverses it on its own; the honest answer is that some of it responds to strength training and protein intake, and some of it is simply the body doing what estrogen decline tells it to do. Anyone selling a supplement that promises to "balance your hormones" and undo this in three weeks is selling something that doesn't match the biology.
What to actually do about it
The single most useful step is tracking symptoms against your actual cycle for two to three months before any doctor's appointment — a simple notes app entry logging period timing, sleep quality, and mood shifts turns a vague "I don't feel like myself" into data a physician can act on. Bring that log in and ask directly whether perimenopause should be on the differential, rather than waiting for the doctor to raise it first. If the answer you get is dismissive, it's worth finding a provider who specializes in menopause care — the Menopause Society (formerly known as NAMS) maintains a searchable directory of certified practitioners in the US, and the British Menopause Society runs an equivalent list in the UK.
- Hormone therapy is not automatically off the table just because a woman is still having periods — perimenopausal HRT and low-dose birth control are both used to manage symptoms, and the decision depends on individual health history, not age alone
- Strength training two to three times a week does more for the midsection weight shift than cardio alone, largely because muscle mass itself starts declining faster once estrogen becomes erratic
- Sleep disruption in perimenopause is frequently driven by night sweats even when a woman doesn't register them as hot flashes — cooling sheets and a lower bedroom temperature help, but if waking is frequent and unexplained, it's worth naming to a doctor specifically as a possible hormonal symptom
The workplace hasn't caught up either
It isn't only medicine that's behind — employment policy is too, though the UK has moved further than the US on this front. In 2023, amendments to workplace equality guidance formally recognized menopause-related discrimination as a potential form of sex and age discrimination under the Equality Act, and the government appointed a Menopause Employment Ambassador to push employers toward practical accommodations like flexible scheduling and temperature control in offices. No equivalent federal policy exists in the US, which means women navigating symptoms at 37 or 38 are frequently doing it without any formal workplace language to describe what's happening, let alone protections tied to it.
One symptom that rarely gets connected to perimenopause, even by women experiencing it, is joint pain — particularly frozen shoulder, a condition where the shoulder joint stiffens and loses range of motion over months. Research has found a disproportionate rate of frozen shoulder in perimenopausal and postmenopausal women, tied to estrogen's role in maintaining connective tissue elasticity. A woman who develops sudden shoulder stiffness in her late thirties is far more likely to be referred to physical therapy for a rotator cuff issue than to have anyone raise hormones as a contributing factor, even though the timing frequently lines up exactly.
The part that's easy to miss
Not every mood change or skin flare in your thirties is perimenopause, and it's worth saying plainly: over-attributing every bad week to hormones can delay real diagnoses of thyroid disease, iron deficiency, or depression just as easily as under-attributing symptoms delays a perimenopause diagnosis. The goal isn't to slap a trending label on everything — it's to put perimenopause back on the list of possibilities a doctor actually considers, instead of leaving it off entirely because a patient is 36 and doesn't fit the outdated picture of what that transition is supposed to look like.
What "second puberty" got right, as an internet phrase, is the recognition that something real and physiological is happening to a lot of women earlier than anyone told them to expect. What it can't do is replace an actual diagnosis. Track the pattern, bring the data to someone trained to read it, and don't accept "you're too young for that" as a final answer without at least one follow-up question.