23 Weeks Pregnant: Getting Ready for the First Breath

Last week, your baby was busy learning the shape of itself by touch. This week, deep inside that growing little body, the lungs begin one of the most important projects of all. Getting ready to breathe.

Welcome to week twenty-three. Your baby is preparing, piece by piece, for life in the world out here, growing stronger and more capable by the day, and reaching a quiet, hopeful milestone along the way. Let me show you.

Your baby's lungs are getting ready to breathe

Deep in your baby's chest, a long and careful project is underway.

Your baby's lungs are growing their delicate branching airways, like the finest upside-down tree, and weaving tiny blood vessels all around them, ready one day to pass oxygen into the blood. And this week, special cells begin to make the first traces of something quietly miraculous, called surfactant.

Surfactant is a slippery substance that coats the inside of the lungs and stops the tiny air sacs collapsing and sticking shut. Without it, lungs cannot stay open to breathe. With it, they can. Your baby is beginning to make it now, in the smallest amounts, months before there is any air to use it on.

The lungs are not ready yet, and will not be for a good while still. But think of what this means. Your baby has been practising the motion of breathing for weeks now, the chest rising and falling on fluid. And this week, the lungs themselves quietly begin to prepare, piece by piece, for the single most important breath of your baby's life. The one that comes in the bright air of the delivery room and turns into that first, unforgettable cry.

Which way is up?

Here is a delightful little change this week. Your baby develops a sense of balance.

Deep in the inner ear, the tiny organ that tells us which way is up has matured enough to begin working. So as your baby floats and tumbles and rolls in there, they can now sense their own position, whether they are the right way up, lying sideways, or in the middle of one of those somersaults you may be starting to feel. It is a brand new way of knowing the world, and themselves, in the dark.

A quiet milestone of strength

There is a tender milestone that falls around this week, and I want to share it gently.

Your baby has grown so strong, and come so very far, that should they arrive early now, there is a real chance that, with the dedicated care of a neonatal team, they could survive out in the world. It is not something most mothers will ever need, and I hope with all my heart you have a long, uneventful wait ahead, with your baby growing snug and safe exactly where they are. But it is, all the same, a quietly astonishing marker of just how capable your little one has become. From a single cell to this, in twenty-three weeks. Remarkable does not quite cover it.

How big is my baby at 23 weeks?

Around twenty-nine centimetres now, head to heel, and roughly five hundred grams. Your baby has started adding fat in earnest this week, beginning to fill out and round off, though the skin is still thin and a little see-through for now.

Long, lean, strong, and busier than ever in there.

What is happening in my body?

You are probably feeling plenty of movement now, real kicks and rolls and jabs, and getting to know your baby's busy times and their sleepy ones.

Your bump is growing, and you may notice the occasional painless tightening, those Braxton Hicks practice contractions, as your body quietly rehearses for the work ahead. Many women find this a comfortable, steady stretch of pregnancy. If you are one of them, lovely. And if you are wrestling with aches, heartburn, or restless nights, that is very common too, and worth a gentle word with your midwife if anything is wearing you down.

From Courtney. This is a week that means a great deal to me, because of where I have spent so much of my working life. In the neonatal unit, I have cared for babies who arrived around this point in pregnancy, impossibly tiny, and watched them fight and grow and, so often, go home in their parents' arms. They are some of the strongest little people I have ever met. I tell you this not to frighten you, but for exactly the opposite reason. Your baby, the one kicking away inside you right now, is far tougher and more capable than their size suggests. Those lungs learning to ready themselves, that new little sense of which way is up, all of it is your baby quietly getting ready for a world they will, when the time is right, be more than ready to meet. Rest easy this week, mama. They are doing beautifully, and so are you.

The one thing to do this week

This week, try this gentle little moment. When you can, sit somewhere quiet, rest a hand on your bump, and take a few slow, deep breaths of your own. Feel your chest rise and fall. Somewhere inside you, your baby is slowly learning to do the very same thing, getting ready for their first breath of air. There is something steadying in breathing together, even now, before they have ever taken a breath at all.

And then, as ever, rest if you need to. You are carrying a great deal, in every sense.

Coming up in week twenty-four

Next week, your baby begins to truly respond to the world. The sounds around them, and most of all the sound of your voice, start to stir a reaction, a kick, a shift, a quiet settling. And the brain grows at a tremendous pace, wiring itself up by the billions.

Week twenty-four is where your baby starts to respond to you. I will see you there.

Written by Courtney Garland, NICU nurse, lactation consultant and mother of four, and founder of The Mama Years. This is here to inform and reassure you. It is not a substitute for medical advice, so always follow the guidance of your own doctor or midwife.

The Mama Years. 2026.

References

American College of Obstetricians and Gynecologists. (n.d.). How your fetus grows during pregnancy. https://www.acog.org/womens-health/faqs/how-your-fetus-grows-during-pregnancy

Cleveland Clinic. (2023). Fetal development: Stages of growth. https://my.clevelandclinic.org/health/articles/7247-fetal-development-stages-of-growth

Mayo Clinic. (2025). Fetal development: The second trimester. https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20046151

Merck Manual. (2024). Stages of fetal development (Consumer Version). https://www.merckmanuals.com/home/women-s-health-issues/normal-pregnancy/stages-of-fetal-development

The Mama Years is written by Courtney Garland, a NICU registered nurse and IBCLC lactation consultant, against the research. When the science is genuinely unsettled, she says so instead of guessing. Nothing here replaces the advice of the clinician looking after you.