The identity shift no one warns you about when you become a mum

You expected feeling totally shattered. You expected the love. But I’m guessing that nobody told you that you'd feel like a completely different person.

You've probably heard the phrase "mum brain" — said with a laugh, usually when you've forgotten why you walked into a room or put the car keys in the fridge. It’s a phrase that’s thrown around constantly but drives me insane as I think it’s actually slightly offensive!

What if I told you, it's not a joke? That your brain literally changes when you become a mother? This change isn’t temporary; it’s not just a little bit. It structurally changes in ways that are still measurable many years later.

And what if I told you there's also a word for the whole thing — the physical changes, the emotional upheaval, the feeling of not quite recognising yourself anymore — and that it's been around since the 1970s, but most of us have never heard of it? I only heard about a year or so after giving birth after listening to the brilliant podcast Motherkind.

The word is matrescence.

What is matrescence?

Matrescence is the process of becoming a mother. Not just the birth, or the first few weeks — the whole identity shift that happens when a new person arrives and your entire life rearranges itself around them. The term was coined by anthropologist Dana Raphael in 1975. She saw that we had a word for the transition from child to adult — adolescence — but nothing for the equally massive transition into motherhood.

Think about that for a second. We accept that teenagers go through a turbulent, hormonally driven identity shift. We expect it. We make allowances for it. We study it in textbooks and as parents, we brace ourselves in preparation for the changes that are coming.

But when a woman goes through something just as profound — often more so — we hand her a baby, check that she’s taking home the child in a correctly fitting car seat and say ‘enjoy every moment.’ The word matrescence isn’t even in the dictionary, which shows how little it’s really talked about. We are finally starting to wake up to the menopause and the impact that it can have, but we’ve clearly got a long way to go before matrescence hits the mainstream.

What actually happens to your body and brain?

Here's where it gets properly interesting (and slightly mind-blowing).During pregnancy, your body increases production of oestrogen and progesterone by up to 1,000 times their normal levels. These hormones don't just support your baby's development — they physically reshape your brain. Then, within 24 hours of giving birth, they crash by about 90%.

At the same time, oxytocin and prolactin surge — wiring your brain to bond with your baby and prioritise their needs over everything else (including yourself). And cortisol stays high, which is why you can't sleep even when the baby's sleeping, why you bolt awake at the slightest sound, why there's a constant background hum of worry. It's not anxiety as a personality flaw. It's your biology doing exactly what it was designed to do: keeping your baby alive.

A landmark study published in Nature Neuroscience found that pregnancy causes reductions in grey matter volume across roughly 80% of the brain. The changes are so consistent that a computer algorithm could predict with 100% accuracy whether a woman had been pregnant just from her brain scan. This isn't damage — it's fine-tuning. Your brain is sharpening the circuits you need most as a mother: reading your baby's needs before they can tell you what's wrong. These changes aren't temporary. They're measurable two years after birth, and some research suggests they leave a permanent imprint traceable decades later.

Your brain also has something called the default mode network — it's the system that's active when you think about yourself, your needs, your desires, your identity. During matrescence, this network gets deprioritised. Your brain literally turns down the volume on self-focused thinking and turns it up on other-focused processing.

Ever said to yourself since having a baby 'I don't even know who I am anymore'? It's not that you're failing to cope. It's a major neurological shift that none of us are ever told about. Your brain has temporarily reorganised its priorities, and the pre-baby you has been moved down the list.

So what does this actually feel like?

As with anything, it depends on who you are as an individual and what your life looked like before. But for a lot of women — especially women who had a strong career identity, who were ambitious, driven, and used to knowing exactly who they were — it can feel like the ground has shifted under your feet.

Some of the things I hear from clients (and honestly, some of the things I've felt myself):

• ‘I don't recognise myself.’ You look in the mirror and see someone else. Not just physically — although that too — but the way you think, what you care about, what motivates you. The person who used to be so certain about everything now isn't sure about anything.

• ‘My career doesn't feel right anymore.’ The job you loved before maternity leave feels flat. Decisions that used to come easily now feel effortful. It's not that you don't care about work or don’t want to work — it's that your relationship with it has fundamentally changed, and no one told you that was going to happen.

• ‘I feel guilty all the time.’ When you're at work, you feel guilty for not being with your child. When you're with your child, you feel guilty for wanting to work. You can't win. This constant push-pull is exhausting, and nobody really seems to acknowledge that it’s a normal part of the process.

• ‘I've lost my confidence.’ You were an expert in your field. You knew how to measure progress, how to improve, how to perform. You were known as great at your job and the person that people came to when things needed doing. Then you brought a baby home, and suddenly you're a novice at the most important job you've ever had. For someone whose self-worth was built on competence, that's destabilising.

• ‘I feel like I should be happier.’ You love your child. You're grateful. But something feels off, and the fact that you can't pinpoint what makes you feel guilty for even noticing it. You also don’t want to tell anyone this for fear of judgement.

Why am I banging on about this?

Because if nobody tells you this is normal — that it has a name, that there's biology behind it, that millions of women experience it — then you're left thinking there's something wrong with you.

You're not broken. You're not ungrateful. You're not losing it. You're in matrescence.

And just like adolescence, it's messy and uncomfortable and disorienting. However, it’s also a process and it does settle. You don’t stay as an adolescent teenager all your life, and it’s the same with matrescence. You do come out the other side. Not as the person you were before, but as someone who integrates both versions of yourself into something new.

Research suggests this identity integration takes roughly two to three years. So if you're six months in and feeling like you'll never feel like yourself again — you're not even halfway through. Give yourself some time.

What you can do right now to help:

You don’t have to just get on with it. There are some things that will genuinely help if you are going through this:

• Name it. Seriously — just knowing the word "matrescence" and understanding what's happening in your brain can be a huge relief. You're not falling apart. You're developing.

• Stop trying to get back to ‘normal.’ The goal isn't to recover your pre-baby self. As hard as it might be to hear it, you will never go back to the person who you were before children. The goal is to figure out who you are now — and what you actually want from your career, your relationships, and your life at this stage.

• Talk to someone who gets it. Not someone who'll tell you to enjoy every moment or that it goes so fast. Someone who'll sit with the messy, complicated truth of it and help you work through what it means for you.

• Give yourself a realistic timeline. You wouldn't expect a teenager to have their identity figured out in six months. It’s the same with matrescence.

If any of this sounds familiar, that's kind of the point. I work with ambitious mothers who are navigating exactly this — the identity shift, the career question, the "what do I actually want now?" If you want to talk it through, I’d love to hear from you.