I was in my 30s when I started suffering unexplained stomach problems, fatigue and mood swings. To my shock, it turned out to be perimenopause. This is why it can start earlier than you think

Your stomach cramps, your head pounds and there’s a foggy feeling in your brain that just won’t shift.

For many women in their 30s, symptoms such as brain fog, chronic fatigue, digestive issues and migraines are commonplace. When they book a consultation with their doctor, they are dismissed with diagnoses of stress, Irritable Bowel Syndrome (IBS) or lifestyle fatigue. But what if these symptoms, when put together, could reveal another cause?

The reality behind these unexpected problems could actually be something rarely discussed in younger age groups: perimenopause.

While the conversation around midlife hormonal shifts has grown in recent years, misconceptions about when this transition begins, and how long it might last, are still rife. Around one in 100 women experience menopause before the age of 40, a condition medically defined as Primary Ovarian Insufficiency (POI). Yet millions more in their late 30s begin experiencing the early, turbulent waves of perimenopause without realising it.

Sonia Dunleavy, 50, from Buckinghamshire, was just 42 when she went through menopause. For years, she had visited her GP and paid to see specialist doctors to try and curb symptoms that plagued her life, but she was always sent away with a different answer.

‘From my early 30s I experienced awful stomach issues,’ she says. ‘It came to the point where I was afraid to leave the house in case I needed the toilet. But doctors just said it was IBS. Then I began to experience chronic fatigue. I was a single mum holding down a full-time job – but this wasn’t just tiredness, it was utter exhaustion.

Sonia Dunleavy, 50, was just 42 when she went through menopause

Sonia had struggled to conceive but never considered that her disrupted hormone issues could be a sign of perimenopause.

‘I also suffered terrible mood swings,’ she says. ‘I called them my mood rages! But my GP was more keen to offer me antidepressants than do any further investigations or put all the symptoms together and understand the whole story.

‘I became very anxious. I worried about what might be wrong with me and I hated the fact that I felt I couldn’t cope. I have always been strong and confident but years of being fobbed off left me anxious and unhappy.

‘I now know I was in perimenopause and just feel that if somebody had listened, they could have pieced the symptoms together and I could have got help a lot sooner. I wasn’t prescribed HRT until after my actual menopause. I feel my life could have been so different if I had got support when I needed it.’

Sonia wants the conversation around perimenopause to be opened up and for medical practitioners and workplaces to understand that perimenopause is not just a ‘midlife’ problem – it can happen to women who may still be raising a young family.

Dr Charis Chambers is a board-certified obstetrician-gynaecologist and chief medical officer at symptom-tracking app Clue. She says the initial problem is that the medical definition of menopause itself is often misunderstood.

Dr Charis Chambers says the medical definition of menopause itself is often misunderstood

‘Menopause is technically not a years-long period of symptoms, but a single point in time – precisely one day – marking 12 consecutive months following a woman’s final menstrual cycle,’ she says. ‘Once that 12-month cessation period is complete, a woman enters post-menopause.

‘Perimenopause – the hormonal precursor to this milestone – can commence up to ten years before that final menstrual period. This means women in their mid-to-late 30s can spend years navigating profound hormonal fluctuations while remaining completely in the dark.’

Dr Chambers says that, up until now, traditional medical training has focused almost exclusively on the classic, easily identifiable signs of oestrogen decline. When women mention hot flushes, night sweats and irregular periods, GPs quickly identify an onset of perimenopause.

But while these textbook symptoms are widely accepted as key indicators of perimenopause, relying solely on them leaves vast numbers of younger perimenopausal women overlooked, as early-stage perimenopause can often occur without a single hot flush in sight.

‘Because oestrogen receptors are distributed throughout nearly every tissue in the female body, fluctuating hormone levels during perimenopause can unleash a confusing array of lesser-known symptoms across multiple biological systems,’ says Dr Chambers.

‘One of the most significant yet underreported areas affected is the digestive tract. Hormonal shifts frequently cause unexpected changes in gut health, including a sharp increase in acid reflux due to the relaxation of the lower oesophageal sphincter.’

So while many women may put their change in toilet habits or episodes of reflux down to ‘wine o’clock’ or a spicy meal, it could be an indicator of perimenopause.

‘Women in their 30s may still be raising toddlers but experiencing perimenopausal symptoms,’ says Dr Chambers. ‘Women are having children later, and they are combining parenthood with careers and other responsibilities. What could be put down to postpartum hormone shifts could actually be perimenopause.

‘When a woman keeps getting headaches she may think it is stress, but the chance of suffering migraines increases during perimenopause due to hormonal shifts, so that could be another sign. The good news is that they tend to recede once menopause is done!’

When bowel habits change for women in their 30s, or they suddenly start to experience severe bloating, the immediate thought is not usually one connected to perimenopause.

But Dr Chambers explains: ‘Declining oestrogen impacts the integrity of the gut mucosa and alters the balance of the gut microbiome, leading to painful bloating, sluggish digestion and heightened food sensitivities. And hormonal fluctuations can cause digestive shifts, including increased reflux from oesophageal relaxation.

‘Beyond the digestive system, oestrogen withdrawal acts as a powerful trigger for neurological and dermatological changes. Sudden drops in hormone levels can cause debilitating headaches or severely worsen pre-existing migraines during the transition.’

Many women in their late thirties also report seemingly unrelated symptoms, which all actually come down to a decline in oestrogen and shifting hormone balances:

Because these lesser-known signs closely mimic other common health conditions, perimenopausal women can face obstacles in achieving a diagnosis of perimenopause, so they miss out on treatment that could be offered at the early stages.

Dr Chambers says that digestive disturbances are often misdiagnosed as IBS, recurring head pain is often categorised as stress-induced migraines, and fatigue or mood alterations are routinely attributed to thyroid disorders, clinical depression or burnout.

Compounding the problem, conditions such as endometriosis, thyroid disease and autoimmune disorders can either overlap with perimenopause or coexist alongside it.

Dr Chambers says: ‘Provider bias and gaps in GP medical training create barriers to timely, accurate perimenopausal care. When a 38-year-old woman presents with reflux, bloating and migraines, perimenopause is rarely the first diagnosis a doctor considers.’

But with increased awareness of the possible onset time of perimenopause, and a few self-help tools, Dr Chambers says women can educate themselves to recognise the signs in time and seek help at an early stage.

Hormone blood tests are now considered unreliable during perimenopause – due to sharp daily, and even hourly, hormonal fluctuations – so a concrete history of symptoms over time provides the most accurate diagnostic picture.

‘Systematically logging symptoms, cycle changes, sleep patterns and physical changes such as breast firmness or tenderness creates a comprehensive record that enables doctors to spot underlying hormonal patterns,’ she says.

It can help to create a record that enables doctors to spot underlying hormonal patterns

‘Tools such as Clue operate as valuable daily tracking systems that support body literacy without providing direct medical diagnoses, empowering women to take agency over their health data.’

She says that when visiting their GP, presenting three to six months of documented symptom history can make it significantly harder for concerns to be brushed aside as general stress or isolated health incidents.

Dr Chambers says it is important to remember that medical treatments during perimenopause do not aim to stop or reverse the natural biological transition; rather, they are designed to restore hormonal balance, alleviate distress and safeguard long-term quality of life.

‘Any treatment plan must be carefully tailored to align with a woman’s personal health history, medical risk factors and personal fertility desires,’ she says. ‘Particularly for women in their late 30s who may still be actively planning to conceive.’

By understanding the perimenopause timeline, recognising lesser-known symptoms and presenting documented evidence to their GP, Dr Chambers says women can navigate perimenopause proactively and secure the support they deserve.