17 Weird Things Babies Do In The Womb
Disclosure: I may get commissions when you click through the affiliate links (that are great products I stand by) on my articles. You can read the full disclosure for more information. Content is intended for informational purposes only and does not constitute medical advice.
Carrying a baby for nine months is an extraordinary human journey filled with wonder, joy, and surprises along the way. As new parents eagerly await to meet their bundle of joy face-to-face, it’s fascinating to discover all of the remarkable things happening with their developing baby and all the weird things babies do in the womb throughout pregnancy!
Ready to learn all the weird things babies do in the womb?
From peeing in the amniotic fluid to possibly shedding tears, here’s a glimpse into 21 of the weird and wonderful things babies are up to behind the scenes while still in utero.
1. Drink and pee in the amniotic fluid
Can you imagine swimming around and drinking your own pee? As weird as it sounds, that’s exactly what babies do in the amniotic fluid inside the womb! Amniotic fluid cushions babies inside the uterus and by 20 weeks most of it is composed of fetal urine!
The kidneys begin developing during the first trimester and start producing urine by week 9. Over the coming weeks, babies drink more and more amniotic fluid. They continue ingesting this mix until around week 20 when their kidneys mature enough to process fluids without taking it back in.
2. Practice wailing
Those last weeks of pregnancy can’t pass quickly enough for anxious parents awaiting their baby’s birth. But while parents stare endlessly at the calendar, their baby is actively testing out their brand new vocal cords inside the womb! Third-trimester babies can be observed on ultrasounds rhythmically opening and closing their jaws in crying motions without making an audible peep.
This helps strengthen throat muscles essential for letting out healthy screams, crying and other vocalizations as newborns enter a loud world outside the womb. Soon enough, parents will hear their babies perform their musical stylings firsthand!
3. Bob along with the beat
Parents eagerly countdown feeling those first sweet flutters of baby’s movements. But babies don’t hang out passively while waiting to be born. In fact, researchers have found that babies respond to external rhythmic sounds remarkably early.
As early as 16 weeks gestation, babies have been observed bobbing their tiny heads and bouncing their growing bodies as if dancing along to music playing outside the womb. It’s no wonder many moms report their baby seems to start grooving in the womb when hearing certain singers or songs!
4. Strum their own umbilical cord
Tuning into sounds is vital preparation for a baby navigating the noisy outside world after birth. Babies spend loads of time carefully listening to maternal noises like mom’s heartbeat, voice, and digestive gurgles crucial for development and bonding. But what other instruments might baby be playing behind the scenes?
Surprisingly, moms have reported ultrasounds have revealed their unborn babies gently and rhythmically strumming their own umbilical cords! This stimulates nerves running through the cords sending sensory signals back to your baby’s developing brain. Pretty cool fetal skill to add to the baby brag book!
5. Practice breathing techniques
Although babies don’t use their lungs to breathe until birth, that doesn’t stop them from actively rehearsing this vital survival technique in advance. During the second and third trimester, unborn babies can be seen taking breath-like movements of inhaling amniotic fluid and then exhaling back out. This might happen up to 44 times an hour preparing their lung muscles for the intense workout of respiration after entering the outside world.
It’s incredible witnessing an unborn baby diligently practicing such an essential life skill while still comfortably floating in the womb!
6. Smile with glee
Few things melt a parent’s heart faster than catching their newborn flashing an adorable, gummy smile. But amazingly, babies smile long before being born. In the second half of pregnancy, 4-D ultrasounds have revealed unborn babies smiling, possibly in response to endorphin and dopamine bursts.
And even more amazing and endearing? Researchers believe they primarily smile in their sleep, probably enjoying some funny dream adventures!
7. Taste and smell mom’s meals
Parent’s worries about eating the right foods during pregnancy are justified. Shockingly, babies have functioning taste buds by week 14 of development which researchers believe allows them to detect flavors in amniotic fluid! Babies gulping down amniotic fluid get sampling hints of what mum eats several hours earlier.
There is also evidence that fetuses respond with faster heart rates or increased swallowing to certain foods or stronger-tasting foods mom eats like garlic. The thinking is these early flavor experiences may shape food preferences after birth and nursing. So, eat up, moms!
8. Flex tiny fingers and toes
Curled up tight inside the protective amniotic sac, babies have restricted room for flailing arms and leg kicks seen with newborns. But that doesn’t stop tiny fingers and toes from getting some action! In those first few weeks from just 16 weeks gestation, babies can be glimpsed on ultrasounds using their minuscule hands to gently touch the umbilical cord, mouth, and face for sensory exploration and coordination practice.
And babies wiggle their teeny fingers and toes constantly preparing for all the grasping and walking in their future. Soon those snuggly booties won’t contain all that wiggly action!
9. Display complex emotions
Pregnancy grunts and groans aside, moms endure a rollercoaster of emotions during those 40 vital weeks. But what emotional dramas might the baby experience along the way? Researchers theorize fetuses display excitement, distress, anger, and joy even with their eyes fused shut.
4-D scans reveal third-trimester babies frown, grimace, or smile in response to outside stimuli like loud noises or mom’s laughter. Their developing nervous systems and brains go through critical growth supporting basic emotions!
10. Hiccup to strengthen lungs
Few pregnancy symptoms perturb moms-to-be like relentless hiccups. But did you know your baby gets the hiccups too inside the womb? Researchers found full-term fetus hiccup episodes lasting over 6 minutes! Unlike adults, the cause remains a mystery but may relate to amniotic fluid changes.
The good news is experts believe fetal hiccups serve the vital purpose of conditioning the nervous system and maturing a baby’s developing lungs in preparation for those first breaths at birth. So next time your baby gets the case of hiccups in utero, sit back and smile knowing it’s great practice for their debut into the real world soon enough!
11. Twitch and turn in REM cycles
The last trimester is notoriously exhausting as round ligament pain, heartburn, and midnight bathroom runs further prevent rest. Although cocooned in a quiet, dark world, babies actively cycle between active and sleep states inside the uterus.
Scientists found that at 30 weeks gestation, approximately 80% of their sleep is in a REM sleep state when vivid dreams occur. Twitching limbs, grimaces and smiles suggest unborn babies transparently go through intense dream states. No wonder newborns seem happiest when sleeping those first weeks. They got loads of practice in!
12. Respond to light and sound
That final countdown to birth means lots of curious poking, prodding, and monitoring of pregnant mum from the outside. Parents speak endlessly to their swollen bellies. And noisy ultrasounds constantly bombard the uterus.
Remarkably, babies react to such external stimuli from light and sound. Research reveals babies rapidly adapt their heart rates in response to sudden loud noises nearby. Ongoing research is focussed on whether babies turn away or shield their eyes from abrupt bright light shined near the uterine wall. Of course too much disruptive stimulation isn’t advised, but it is comforting to recognize your baby’s reactive capabilities are so vital for the transition Earthside.
13. Kick up a storm
As pregnancy progresses, life inside mom’s expanding belly transforms into a baby dance party complete with vigorous kicks, startles, and stretches against the uterine wall. And research confirms that third-trimester babies spend a lot of their time actively wiggling arms and legs to promote bone and muscle growth for their impending eviction. These forceful jabs also naturally (and painfully!) strengthen abdominal muscles benefiting labor.
Additionally, feeling movements are reassuring for moms confirming baby is active and healthy late in pregnancy. Soon these short-lived kicks and hits will transition into exasperating flailing limbs keeping parents busy for years postpartum!
14. Play footsies with their sibling
Moms pregnant with multiples get asked if the babies play or cuddle together inside the womb. And incredibly – they do! Ultrasounds reveal twins snuggled close in the womb.
Later on, siblings play footsie, stroke each other’s head and back, and may choose to reach more for their twin than themselves! Researchers believe this stimulates their tactile development and promotes bonding before birth. Of course, crammed womb quarters also mean twins kick, shove, and annoy each other in utero too! But mostly, they seem to enjoy their sibling’s built-in womb company.
15. Gulp down gallons of fluid
Ever wonder where all those dirty diapers come from? Well, babies do tons of practice runs peeing before they’re even born! Fetal urine makes up the majority of amniotic fluid they grow in. Researchers estimate babies swallow gallons of this fluid during pregnancy from constantly opening and closing their jaws.
Then their kidneys process this amniotic mix, filter wastes and send volumes back out as pee. This cycle speeds up late in pregnancy when the kidneys mature. So no wonder newborns arrive primed and ready to fill diapers on the daily for exhausted parents!
16. Sport lush locks
Few things beat that soft fuzz gracing a newborn’s head those first days of life. But surprisingly, babies begin sprouting those first hairs while still developing in utero! Lanugo hair coverage peaks by week 28 gestation as a protective layer shielding delicate fetal skin from amniotic fluids. Babies can grow up to several more inches of hair before birth too.
However, most babies shed this fine, downy hair right before birth. But take heart – that luscious hair will return within months leaving parents grooming mane mane mounds in the future!
17. Practice breastfeeding
Third-trimester babies also seem to rehearse one essential newborn skill in the womb – eating! Scientists have noticed babies frequently moving their mouths open and closed while they “breathe” in the amniotic fluid. This suck-swallow motion mimics the coordinated tongue movements they will soon use for breastfeeding after entering the real world so some say the baby is practising for nursing!
Enjoy the journey and get ready for the whirlwind!
Becoming a parent is about to transform your life in unimaginable ways. But while you eagerly await your baby’s arrival, take a moment to marvel at the incredible preparations and changes happening behind the scenes over 40 weeks of an extraordinary pregnancy journey. Babies work relentlessly strengthening lungs, practicing survival reflexes, interacting with siblings and responding to stimuli readying them for the outside world.
Soon you will meet face-to-face the culmination of all this awe-inspiring fetal effort. So until then, sit back and smile thinking about your baby drinking their own pee poolside and rocking out to your favorite tunes in utero. The countdown is on to cradling the wondrous being you’ve nurtured so closely all these months!
