How Do Babies Get Oxygen In The Womb? It's Time We Cleared The Air

Ad failed to load

When I was pregnant with their little brother, my boys would daily assault me with an endless stream of questions. Some were cuter: "How does he eat in there?" While others had me rolling my eyes: "Does he poop inside of you?" But all were actually pretty valid and I more or less felt capable of answering them accurately. Until one day when my 7-year-old asked if the baby could breathe inside my tummy. Cue the sudden realization that I, the legit grownup, actually had no idea. How do babies get oxygen in the womb? Mommy doesn't know, kids. Luckily, there are some experts who do.

Babies don't exactly breathe oxygen in the womb, at least not in the sense that we understand breath, but they do receive oxygen from the mother. Rebecca Lee, a Registered Nurse in NYC and founder of, explains that when the mother breathes, oxygen is passed from the placenta to the umbilical cord and on to the baby via the bloodstream.

If your baby isn't actually breathing, why does it look so much like he is when you have an ultrasound? Certified Nurse Midwife Katie Page tells Romper, "In the womb, we can see 'breathing' of babies by increase and decrease in the spaces between the ribs." Page says that rather than the lungs actually filling with air, this practice breathing is the chest wall expanding and contracting and the muscles working. Babies don't breathe in the womb, but they sure are committed to practicing.

Ad failed to load

So when does all this practice begin? You'd think it would be towards the end of the third trimester, right? Believe it or not, practice breaths starts as early as nine weeks gestation when, according to Lee, the baby begins to mimic breathing-like movements. Only a week or two later, before the first trimester has ended, she begins to inhale small amounts of amniotic fluid that mimic swallowing. These skills help her little lungs develop properly (and amaze her very excited mom and dad when they find out).

As the weeks of gestation go on, a baby's practice becomes all the more intricate. By 32 weeks she will be making more advanced breathing movements involving compressions and lung expansion, Lee explains, and by 36 weeks her lungs are considered fully mature and ready for life outside the womb (although health professionals all agree that it's safest to let her reach 39 weeks).

Ad failed to load

Page, who is clearly passionate about her midwifery practice, describes a fetus preparing to take her first breath as a fascinating process. "Physiology is so neat," she exclaims. "When a baby is born they are stimulated to breathe via pressure on the chest wall through the birth canal and the sudden release of pressure when they come earth side." Page adds that the change in temperature and surrounding environment, in conjunction with the stimulation of being touched for the first time, triggers the instinct to take her first breath and fill her lungs with air.

I wish I had known about the ins and outs of fetal "breathing" while still pregnant with my little guy a few months ago. Not only could I have patted myself on the back for knowing the answer to yet another one of my minions' questions, but I could have taken credit for another miraculous part of growing a human being: Supplying him oxygen. Like a boss.

Ad failed to load

As a parent there is nothing quite like witnessing your child take the very first breath of his life. Somehow it's made even a little sweeter knowing that he was practicing for it all along.

Check out Romper's new video series, Romper's Doula Diaries:

Ad failed to load

Watch full episodes of Romper's Doula Diaries on Facebook Watch.

Ad failed to load
Must Reads

These Millennial Parents Are Taking Gender-Neutral Parenting To An Entirely New Level

A woman on the subway looks at my bulbous shape and asks, “What are you having?” I take a deep breath and throw a glance to my 5-year-old. “I’m having a baby,” I say to the woman. “No, no” the woman says laughing as she pushes further. “Are you havin…
By Madison Young

I’m Registered At Babies “R” Us, & I'm Freaking The Hell Out

Hi. My name is Abi, and I’m registered at Babies “R” Us — and I’m freaking out. This may sound silly, but after being a die-hard Toys “R” Us kid, I was so excited to register at their baby store once my husband and I finally got our big fat positive …
By Abi Berwager Schreier

My Daughter Is Obsessed With Being "Pretty" & I'm Way Past Terrified

Last week, when I picked up my daughter after school, she immediately wanted to know if I liked her hair. "Is it pretty?" she asked. Her hair was pulled up into two ponytails that were intertwined into thick, long braids. A shimmering pink and purple…
By Dina Leygerman

7 Things No One Tells You About Having A Baby In Your 20s, But I Will

I was 24 when I found out I was pregnant with my daughter. The pregnancy was a surprise, since I was on birth control (side note: antibiotics and birth control don't mix), but my partner and I decided to continue with the pregnancy and committed to m…
By Candace Ganger

Women Who Miscarry Early Deserve To Grieve — Here's How Hospitals Should Be Helping

When I lost my baby back in 2013, it was because of a very early miscarriage. Because of the little amount of time I spent being pregnant, it was though my child had never really existed, which made the next few years hard — I felt like they had been…
By Risa Kerslake

7 Things I Wish My Partner Had Said To Me In The First Hour After Giving Birth

I don't know if it was the buzz of the surrounding machines, the non-existent cry of our son as the doctors tried to resuscitate him, or the fact that I'd already been through labor and delivery once before, but I knew something was missing after I h…
By Candace Ganger

Moms’ Groups Weren’t For Me, Sorry

I go to my moms’ club everyday of the week, but not usually on weekends. My moms' group is a place I can always count on finding fellow mothers who understand the daily struggles and triumphs of parenthood and of juggling life’s responsibilities. Dep…
By Samantha Taylor

Millennial Women Are Getting Married Later Than Gen X, & The Reasons Why Are Pretty Badass

The battle of the generations seems to come up when it comes to every lifestyle or career choice people make. Women, especially, are an important demographic when it comes to analysts looking at the lifestyle choices we make or the expected milestone…
By Josie Rhodes Cook

I've Had 3 Miscarriages But *Please* Keep Telling Me About Your Pregnancy

I can feel the tension the moment my friend announces her pregnancy. I can hear the forced nonchalant attitude she's willing herself to exude as she fishes for the ultrasound. I know why I was the last to learn that she was expecting; why she keeps l…
By Danielle Campoamor

7 Early Signs You're Going To Need An Epidural, According To Experts

Even if you've constructed an elaborate birth plan, it's impossible to control every aspect of labor and delivery. Complications can occur, proactive measures might be necessary, and your mind is subject to change when those damn contractions really …
By Candace Ganger

I'm Pregnant & I Refuse To Read Any Parenting Books

I didn't read any parenting books when I was expecting my daughter, and I refuse to read any parenting books as I await my second child now. I'm the first to admit that I don't really know what I'm doing when it comes to raising my daughter. A good d…
By Marie Southard Ospina

7 Reasons Why March Babies Are Total Badasses

From the moment you become pregnant, you begin to wonder what your little one will be like. Will they look like you, your partner, or your Great Aunt Edna? Will they be the quiet, thoughtful type or arrive on this planet raring to go? It's fun to ima…
By Caroline Shannon-Karasik

12 Overnight Face Masks To Use To Wake Up Feeling Pampered AF

Spring is right around the corner, and as far as I'm concerned, the sunshine and warm breezes can't come soon enough. But now that we're about to say goodbye to winter, it's a good time to take stock of your facial skincare routine. You know, in the …
By Katie Malczyk

11 Essential Products To Pack In Your Hospital Bag, According To OB-GYNs

The minute you go into labor (or think you're going into labor), chaos ensues. You and your partner are likely to get a little frantic, just like in the movies, so you most definitely want to have a hospital bag packed before the day comes. This prec…
By Abi Berwager Schreier

7 Photos You *Must* Take In The First 6 Months Of Motherhood

In my experience, becoming a mom is like becoming an amateur photographer. There's just something about the need to capture every single coo and sorta-smile that leaves you obsessed with all things photography. I know I couldn't stop taking selfies w…
By Candace Ganger

Here's How Early An Ultrasound Can Actually Determine Your Baby's Sex

From the moment you see those two lines on a pregnancy test, there are a few markers along the way that stand out as especially exciting. Amongst them are hearing your baby's heartbeat and feeling that first, sweet little kick. And if you are finding…
By Caroline Shannon-Karasik

9 Easy Kid Foods To Turn Green, Just In Time For St. Patrick's Day

The best part about having kids is that you get your own personal crew to celebrate the holidays with, in all your color coordinating and matching glory. And with St. Patrick’s Day right around the corner, you are obviously working on turning everyth…
By Mishal Ali Zafar

Here Are Some Conditions That Might Require You To Be On Bed Rest During Pregnancy

When I worked in an office, I worked with quite a few pregnant ladies all at the same time. Something must have been in the water, because while I was there for three years, two of my coworkers got pregnant twice, and another girl was pregnant with h…
By Abi Berwager Schreier

I Didn't Follow The Pregnancy Diet Rules & My Daughter Turned Out Just Fine

My diet is an ever-changing and wholly personal thing, which is precisely why I refused to follow any pregnancy diet rules when I was expecting my daughter. For years, I've essentially practiced intuitive eating, in that I listen to my body and eat w…
By Marie Southard Ospina

5 Foods You & Your Partner Should Eat If You're Trying To Get Pregnant

When you're trying to conceive (TTC) and it's just not happening, it's easy to feel like you're doing something wrong. It can be soul-crushing to keep seeing negatives when all you really want to do is wave a positive pregnancy test in the air. So wh…
By Kate Miller