29 Weeks Pregnant: The Bones That Will Carry Them a Lifetime

Last week, your baby's final sense switched on. This week, your baby gets seriously strong, building a skeleton out of you, and growing big enough that they become a presence you can truly feel.

Welcome to week twenty-nine. Your baby's bones are hardening fast, their movements are turning into pokes and prods you can feel under your hand, and there is a real, solid little person in there now. Let me show you.

Your baby is building a skeleton to last a lifetime

Your baby's bones have been there for a long while, but until recently they were soft and bendy, more like rubber than anything solid. Ever since around week eleven, they have been slowly hardening. And now, in the third trimester, that work goes into overdrive.

This week, your baby's skeleton is soaking up calcium at an astonishing rate, hardening from soft cartilage into strong, true bone. And here is the tender part. That calcium is coming from you. Your body gathers it up and sends it down the cord, making absolutely sure your baby gets what they need to build themselves a frame, even drawing on your own stores to do it. Your body is, quite literally, giving of itself to build your baby, bone by bone.

And think about what that frame is for. These are the bones that will one day hold your baby upright for their very first wobbly step. That will run and climb and dance. That will carry them across a stage, down an aisle, through a whole long life, and perhaps one day carry babies of their own. The scaffolding for all of it is being laid this week, with calcium straight from you.

The week you start to feel a foot

As your baby gets bigger and stronger, the inside of your world is changing too.

There is far less room to swim and somersault now, so those rolling, swooping movements give way to something more pointed. A jab. A poke. A long, slow stretch that pushes out one whole side of your belly. And for the first time, you may begin to feel actual parts of your baby. The hard little knot of a heel tucked under your ribs. The drag of an elbow. The round curve of a tiny bottom pressing up against your hand.

Some evenings, if you watch your bare belly, you might even see it move, a ripple, a bulge, a whole little shape shifting across as your baby turns. After all these months of imagining, your baby is becoming someone you can feel, and very nearly see. A real, solid, wriggling little person, right there under your hand.

A brain taking charge

Quietly, your baby's brain is taking over more and more of the running of their body.

It is steadying the rhythm of those practice breaths, beginning to help regulate body temperature, and coordinating all that kicking and stretching. Bit by bit, your baby is becoming ready to run their own body out in the world, where there will be no cord and no womb to do it for them. The systems that will one day keep them alive are rehearsing now, under the command of that remarkable, folding brain.

How big is my baby at 29 weeks?

Around thirty-eight to thirty-nine centimetres now, head to heel, and roughly one and a quarter kilograms. Your baby is getting properly heavy and strong, packing on fat and muscle, and filling more and more of the space inside you.

Which is exactly why you are feeling them so much more this week. There is a real little person in there now, and they are running out of room to hide.

What is happening in my body?

You are properly into the third trimester now, and your body is working hard.

You might be dealing with heartburn, a tired and achy back, restless legs at night, or breathlessness as your baby presses up under your ribs. You may find yourself needing the loo constantly, with your baby sitting low on your bladder. All of it is normal, all of it is temporary, and none of it makes you ungrateful for feeling tired or sore. Rest as much as you can, accept every offer of help, and keep talking to your midwife about anything that is bothering you.

From Courtney. This is around the time it stopped being abstract for me and became real, with each of mine. Lying in bed at night, I would feel a little heel slide under my ribs, press my hand gently against it, and feel my baby press back. A proper hello, skin to skin through my own belly. And every single time, it floored me to think that the calcium for those very bones, the heel I could feel, the spine, the tiny ribs, had come from my own body. That I was, in the most literal way, building this person out of myself. You are doing that right now, mama, tired and stretched and sore as you may be. You are quite literally giving them the bones to stand on. There is nothing more extraordinary than that.

The one thing to do this week

This week, let the people you love in on it. When your baby is having an active spell, take a partner's hand, or a big brother's or sister's, and rest it on your bump to feel those kicks and rolls. Watching someone's face light up the first time they feel your baby move is one of the loveliest joys of pregnancy, and it helps them start to bond too.

And if you can, pop a little extra calcium into your day where it is easy, a yoghurt, some leafy greens, a glass of milk, to help top up what your busy baby is borrowing. No stressing at all if that is tricky, your body has it covered. And as always, rest those feet whenever they ask for it.

Coming up in week thirty

Next week, your baby's brain grows wrinklier and cleverer still, and a remarkable change begins on the outside. The soft, downy lanugo that has covered them for months starts to disappear, as your baby grows into smoother, plumper skin. They are getting ready, layer by layer, for your arms.

Week thirty is where your baby begins shedding their first coat. 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 third trimester. https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20045997

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.