40 Weeks Pregnant: The Finish Line, and Your Baby's First Breath

Last week, your baby reached full term and may have been getting ready to call the day. This week, you reach the finish line. Week forty. Your due date. The moment all of this has been quietly building toward.

Welcome to week forty. Everything you have read about over these past nine months, every cell, every heartbeat, every tiny fingernail, is about to become a real, warm, breathing baby in your arms. Let me show you what awaits.

Your due date is here, but it is not a deadline

So here it is. The day circled on the calendar all these months. Your due date.

But here is something every mother deserves to know. Your due date was only ever an estimate, a best guess at the middle of a perfectly normal range, not a hard deadline. In fact, only about one in twenty babies actually arrives on their due date. The vast majority come in the couple of weeks either side, and first babies especially often like to take their time.

So if today arrives with no sign of your baby, please do not feel disheartened, and please do not feel that anything is wrong. You have not failed at anything. Your baby is simply not quite ready to make their entrance, and that is completely normal and usually perfectly healthy. Your midwife will keep a close and caring eye on you both from here. Your baby is coming. Just on their own perfect schedule.

The most dramatic moment of their life

Whenever your baby does decide to arrive, they will go through the single most dramatic transformation of their entire life, and it happens in just a few minutes.

For nine months, your baby's lungs have been filled with fluid, and every breath of oxygen they needed came from you, through the cord. Then your baby is born, and everything changes at once. With their very first breath, their lungs fill with air for the first time ever, and the fluid inside them clears away. And in those same few moments, something extraordinary happens in their heart. The little doorways that let blood skip past their unused lungs in the womb swing closed, and their whole circulation reroutes itself, sending blood rushing to those lungs to gather oxygen for the very first time.

In the space of a few breaths, your baby switches from living in water to breathing air, a change so total and so perfectly timed that it will never be matched again as long as they live. And that first thin, furious cry? That is the sound of your baby breathing, all on their own. The sound you have waited the whole pregnancy to hear.

And then, you meet

And then comes the moment all of this has been for.

Your baby, lifted up and laid on your chest, warm and real. And everything you have read about over these past months comes alive at once, right there in your arms. Because your baby already knows you. They will turn toward the sound of your voice, the one they have heard from the very inside. They will calm at the familiar beat of your heart. They will catch your scent and root toward you, searching for the breast, exactly as they practised. And when they finally open their eyes and find your face, the very first face they look for will be yours.

To your baby, you are not a stranger. After everything, from that single cell all those weeks ago, you are the one thing they have always known. You are home. You always were.

How big is my baby at 40 weeks?

Around fifty-one centimetres now, head to heel, and roughly three and a half kilograms, give or take, because healthy babies arrive in all sorts of wonderful shapes and sizes.

Fully grown. Completely ready. And so very nearly in your arms.

What is happening in my body?

You have reached the finish line of pregnancy, and you have likely never felt so ready, or so impatient, in your life.

Watch closely now for the signs of labour your midwife has talked through with you, and trust that you will know when it is time. And if you go past your due date, try not to worry. Your midwife will talk you through how they would like to keep an eye on you and your baby, and what your options are if your baby needs a little encouragement to arrive. Rest, eat, stay hydrated, and gather your strength. The next time everything changes, it will be for real. And it will be worth every single second of this wait.

From Courtney. If you have been with me since those very first weeks, look how far you have both come. From a tiny cluster of cells smaller than a poppy seed, to a whole, complete, breathing baby, ready to meet you. I have loved walking these forty weeks beside you. And now, whether your baby arrives today or makes you wait a little longer yet, I want you to hear this. You have done something miraculous. You grew a person. A heart, a brain, ten fingers, ten toes, a mind, a whole entire human being, made inside your own body. Soon you will hold them, and they will look up at you and know you instantly, as the voice, the heartbeat, the warmth they have loved their whole existence. You are their whole world, mama. You have been all along. Now go and meet them. I am so proud of you.

The one thing to do this week

This week, the one thing to do is to trust. Trust your body, which has grown and carried and readied this baby for nine extraordinary months. Trust your baby, who knows how to be born and how to find you. And trust yourself, because you are so much more ready for this than you feel.

Rest while you can. Keep your bag by the door and your phone charged. And in the quiet moments, remind yourself of the simple, staggering truth of it all. You are about to meet the person you have been growing this whole time. You can do this, mama. You were made for it.

A note for the weeks ahead

If you are reading this with your baby finally in your arms, then congratulations, mama. You did it. Thank you for letting me walk every one of these forty weeks with you. And now your loveliest chapter begins. When you feel ready, switch over to the baby tracker in the Mama Years app, to keep a gentle eye on feeds, nappies, and sleep, and to find guidance and learning matched to your baby as they grow.

And if you are still waiting, please know I have not left you. The next little stretch can feel like the longest of the whole pregnancy, so week forty-one is just for you. The mother who is still carrying, still waiting, and so very ready. I will see you there.

The Mama Years. 2026.