Perimenopause at 35? The Questions I Didn’t Know to Ask

By Ellen Sofie Øgaard

Short answer: Perimenopause is the transition before menopause, when hormones start to fluctuate and periods become irregular. It most often begins in your mid-40s, but it can start in your mid-30s. The first signs are often subtle, such as fatigue, brain fog, anxiety or poorer sleep, rather than hot flushes. It is very individual, and a doctor can help you work out what’s going on.

In my founder story I wrote that I’m 34 and not in perimenopause yet. A few weeks later, Instagram showed me something that made me stop. My algorithm had changed because of all my research, and there was Dr Mary Claire Haver, an American doctor who writes about menopause, explaining that many women with regular periods can start to feel the changes as young as 35. Her new book lists the early signs as anxiety, fatigue, joint pain, brain fog, sexual symptoms and volatile moods.[4]

Thirty-five. I’m 34.

I gave birth to twins a year and a half ago, and I have struggled with brain fog ever since. It has improved a lot since I started taking creatine, which I write about in my founder story. But I realised how easy it would be to slide from postpartum brain fog, to breastfeeding brain fog, to perimenopause brain fog, without ever connecting the dots. How is it possible that I didn’t know this at 34, when I’ve spent years reading about women’s health?

The information isn’t missing. It just doesn’t reach us before we need it. So here are clear answers to the perimenopause questions women google most, with sources. One thing first: this is very individual. Perimenopause doesn’t have to start at 35, and most women notice it later.

What is perimenopause?

Perimenopause is the time before menopause, when your hormone levels start to change and your periods become irregular. Menopause itself is one point in time: when you haven’t had a period for 12 months, and you’re not using hormonal contraception.[1]

So when people say “menopause symptoms”, they often mean perimenopause. That’s the phase where hormones fluctuate most, and where many women first notice that something has changed.

When does perimenopause start?

Most often in your mid-40s, but it can begin as early as your mid-30s or as late as your mid-50s, according to Cleveland Clinic.[3] The NHS says menopause usually happens between 45 and 55, and can happen earlier.[1]

In other words, perimenopause at 35 is possible, but it isn’t the rule. If you’re in your late 30s and something feels different, it’s worth knowing that perimenopause is one of the possible explanations, alongside many others a doctor can help you look at.

What are the first signs of perimenopause?

For many women it’s not the hot flushes we’ve all heard about. Cleveland Clinic describes irregular periods as the most common first sign.[3] Dr Haver lists anxiety, fatigue, joint pain, brain fog, sexual symptoms and volatile moods among the early symptoms.[4]

These are easy to explain away. Tired? You have small children. Forgetful? You’re busy. Anxious? It’s been a lot lately. That may all be true, and it’s exactly why it helps to notice when and how often these things happen.

What are the 34 symptoms of perimenopause?

This is by far the most searched perimenopause question, according to one published list.[6] The “34 symptoms” is a popular list that circulates online. It isn’t an official medical checklist, and you won’t have all of them.

The NHS describes a wide range of possible symptoms, including:[2]

  • Changes to your periods.
  • Hot flushes and night sweats.
  • Difficulty sleeping, and feeling tired.
  • Changes in mood, such as anxiety, low mood or irritability.
  • Problems with memory or concentration, often called brain fog.
  • Headaches, joint or muscle pain, and vaginal dryness or discomfort.

What matters more than the number is which changes affect your life, and how much. That’s what your doctor needs to hear.

Is brain fog a symptom of perimenopause?

It can be. Forgetting words, losing your train of thought and struggling to concentrate are common complaints, and there is research behind them. A large US study followed 2,362 women aged 42 to 52 for four years and found that their learning and memory improved less during perimenopause than before it. The good news: in the same study, it seemed to be temporary, and learning returned to earlier levels after menopause.[5]

Brain fog has many possible causes, though, from sleep loss and stress to a new baby, thyroid problems or low iron. If it’s affecting your work or your days, take it to a doctor rather than deciding the cause yourself.

Is it perimenopause or postpartum?

This is the question I asked myself, and many women in their late 30s and 40s with young children do too. Broken sleep, brain fog, mood changes and irregular periods can all happen after a baby and during breastfeeding. They can also be early perimenopause, or both at once.

There’s no way to tell them apart from a list of symptoms alone. What helps is a record over time: when it started, whether it changes with your cycle, and whether it eases as your baby sleeps more or you stop breastfeeding. Bring that to your doctor, and mention your age, your pregnancy and how you’re feeding your baby.

How long does perimenopause last?

On average about four years, but it can last up to eight, according to Cleveland Clinic.[3] For some women it’s shorter, and for others longer. Symptoms can also come and go along the way, which is one reason it can be so confusing.

Can you get pregnant during perimenopause?

Yes. As long as you still have periods, even irregular ones, you can get pregnant.[3] If you don’t want to, keep using contraception and ask your doctor how long you need it.

Is there a test for perimenopause?

Not a simple one. Hormone levels go up and down so much during perimenopause that a single blood test often isn’t reliable, and hormone testing usually isn’t needed to diagnose it.[3] Doctors normally look at your age, your symptoms, your periods and your medical history.

That’s why your own description matters so much. A short record of what has changed, when, and how it affects your days gives your doctor something real to work with.

When should I see a doctor?

Whenever symptoms are affecting your life. You don’t need to wait until they’re severe, and you don’t need a perfect diary first.[2]

Some changes should be checked rather than put down to perimenopause: very heavy bleeding, bleeding after sex, new bleeding between periods, or any bleeding after your periods have stopped for a year. Contact a doctor about these.

If you’d like help preparing, read How to Prepare for a Perimenopause Doctor’s Appointment.

What I’m doing now

I don’t know if what I’ve felt since the twins is postpartum, perimenopause, or simply life with two small children. But I’ve stopped assuming. I note how I feel, I keep an eye on my cycle, and if the brain fog comes back I’ll bring my notes to my doctor.

If you want to do the same, start small. What to Track in Perimenopause, and What You Can Leave Out shows you how, on paper or in an app. Or try a one-minute check-in on the homepage and see what day 1 of your own record looks like.

And if you’re in your 30s and reading this: who in your life should know it too?

Safety note: This article is educational and not medical advice. Contact a healthcare professional about new, persistent or worrying symptoms, and seek urgent care for severe or sudden ones.

Sources

  1. NHS, What are menopause and perimenopause? Page reviewed 19 May 2026; accessed 4 November 2026.
  2. NHS, Menopause and perimenopause: symptoms Accessed 5 October 2026.
  3. Cleveland Clinic, Perimenopause Medically reviewed, last updated 29 July 2024; accessed 4 November 2026.
  4. Mary Claire Haver, MD, The New Perimenopause (Rodale Books, 2026), publisher’s description Accessed 4 November 2026.
  5. UCLA Health, Menopause transition may cause trouble learning (on Greendale et al., Neurology, 2009) Accessed 4 November 2026.
  6. The Independent Pharmacy, 10 most googled questions about perimenopause Accessed 30 October 2026. The search figures are the publisher’s; its method is not stated.