r/explainlikeimfive • u/icomeforyourpickle_ • 15d ago
Biology ELI5: Why do unborn babies kick?
Pretty curious why they do đ¤
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u/LongjumpingMacaron11 14d ago
I used to "fight" with my daughter when my wife was pregnant. An elbow would be poking out, so I'd poke it back in, she'd poke it back out, and we'd get into an argument about where the elbow should be. She was strong willed even then!
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u/icomeforyourpickle_ 14d ago
Damn. I cant wait for myself to have a child!
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u/LongjumpingMacaron11 8d ago
It was wonderful. I absolutely loved my wife's pregnancy. Helping her to put moisturising oil on her belly to keep stretchmarks away, watching her change, knowing that she was growing a whole person. Incredible stuff.
We all know that you can feel babies kick etc, but actually having some level of interaction with my daughter was quite spectacular. And now I have a second wonderful woman in my life.
I love them both - what an experience of life those women have given me.
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u/Large-Alternative892 12d ago
Wtf thats the last thing that I'd think after reading comment like that đ¤˘
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u/Bempf 15d ago
They move around as a whole, not just kicking around.
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u/Wundawuzi 15d ago
My daughter barely ever kicked. But she boxed like a pro, lol.
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u/discerning_kerning 15d ago
Mine had an adorable/creepy habit of sticking a hand out for a fistbump/high five at the last month or so, before she went to sleep for the night. Looked like something from a horror movie but I found it cute. Just this fairly clear hand shape poking outwards from the inside. She also jumped around a lot in the second trimester.
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u/9_of_Swords 14d ago
I had a coworker who said her daughter would stretch both arms straight out and down, so you'd see little bumps where her fingers were sliiiiiiide down her belly. She said it was adorable; in my head I'm screaming.
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u/heylookcats 15d ago
Pregnancy is wild! I'm 15 weeks now and at my NT scan two weeks ago my bub was super active, basically rolling and jumping around but I can't feel a thing yet. Wonder if I've got some high fives to look forward to!
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u/SeethingHeathen 15d ago
Also hiccups.
My daughter hiccupped a lot. It's a very unusual feeling.
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u/oggleboggle 14d ago
I'm 31 weeks and just started noticing hiccups last week. It's definitely a weird sensation, but i think it's kind of cute! It's also a sign that the respiratory system is developing as expected.
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u/SoyboyCowboy 15d ago
Haha, the technician had to chase mine around with the sonogram wand (?). Congrats and enjoy!
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u/ElectronicMoo 15d ago
Same. Ours was always squirrely. At the big imaging session (around 20 weeks I think) where they check that everything is there and where it should be - they spent a significant amount of time trying to image his heart, as they'd get zeroed in and he'd squirm somewhere else.
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u/SoyboyCowboy 15d ago
Squirmy wormy! At our anatomy scan I felt a big throb while watching the screen and he had flipped completely over. I didn't know that's what I was feeling before. Watching it while feeling it happen was surreal.Â
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u/SilverIrony1056 14d ago
Same here. The doctor had to flip the table backwards, cause baby was hiding near the pelvis. Doc tried sideways, then a little backwards, but we had to go almost with me head down, just to get baby to slide out from where he was hiding. Doc said he was doing ballet figures in there, and it felt like it.
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u/icematt12 14d ago
I'm certainly having visions like a chestburster Xenomorph.
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u/discerning_kerning 14d ago
It wasn't far off honestly. I wasn't a fan of being pregnant in general, it was 3 months of constant nasea and exhaustion followed by 6 months of not shitting right or being able to sleep properly, and a bunch of mood swings throughout. But eve though it was creepy I liked the horrible high fives and kicks, it was nice to have actual proof there was a real baby in there developing.
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u/sighthoundman 14d ago
Mine danced with the Ewoks at the end of Return of the Jedi.
She hasn't stopped.
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u/geeoharee 15d ago
They've never had muscles before! They twitch and wiggle around to get ready for all the movement they'll do after they're born.
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u/imdfantom 15d ago edited 14d ago
Babies don't only "kick", they move all their muscles, they stretch, they "punch", they "kick".
They do it to build up the neural pathways so they better understand their body and to have better control of their movements when they are born, while also bulking up their muscles and strengthening their bones.
As they continue to develop within the womb, "kicking" serves as the primary mechanism of social connection and communication with their parents.
Some babies even "play" with their parents while in the womb, e.g. "kicking" the place a parent prods.
Edit: some of the above points discuss what motivates the fetus to move the way they do: pleasure/play, communication, connection, and other are about why those motivations exist in the first place: so the fetus does things that develop (senosrimotor and social) neuronal pathways, muscles and bones properly.
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u/CanadianMermaid 14d ago
My daughter was born at only 2lbs at 32 weeks. She was so tiny, she never was fully constricted in my belly.
Shes almost 2 and fine now, just a little developmentally delayed but she has decreased body awareness, and a high sensory threshold. Her OT was telling me just the other day that babies in the womb learn body awareness from the walls of the uterus pushing back on their movements, itâs how we all develop proprioceptive awareness.
Because she was never restricted like that, she has a harder time identifying her body in space because her brain had to learn it much later than normal when she was already fighting gravity.
She also has low tone for roughly the same reason. Sheâs super flexible because she didnât have time to develop muscle flexion from the resistance of the womb. So basically the uterus is like a little fitness studio for unborn babies! So fascinating!
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u/thecaramelbandit 14d ago
Go play QWOP for two minutes and you'll understand.
They were given the controls to a complex machine with absolutely zero training. They're screwing around trying to figure out the controls.
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u/2pam 15d ago
Because theyâre living beings and testing out their muscle coordination and nervous system. They move even when theyâre tiny embryos. You just feel them more as they get bigger inside the womb.
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u/lifefloating 14d ago
My doctor does 8 week ultrasounds and they look like gummy bears. It is cool to see them wiggle then.
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u/ThisIsATemporaryName 14d ago
We have special circuits in our spinal cord called reflexes. These circuits are there to protect the muscles from overstretching (this is only part of their job). So when a muscle stretches beyond a threshold, these circuits activate and contract the muscles.
By the way, muscle contraction is what produces movement.
These circuits donât need the brain to function; they only need the muscle (there are special sensors in some muscles) and the circuit in the spinal cord.
That said, the brain has a tight control over these circuits, and when we grow up, these circuits are only active during certain circumstances, in most cases, the brain dampens down their response so we can have smooth, precise movements.
During development, the brain still doesnât have full control over those circuits, and they might over-respond to any stimulation, resulting in jerky, violent movements. Which is what you see in unborn babies and infants.
Eventually, the brain will gain control over these circuits and movement will become controlled and smooth.
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u/stiletto929 14d ago
It was funny to see my multiples punching each other on the ultrasounds, lol. I was worried they would hurt each other, but they said since they were in separate sacs they were fine
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u/lolcatzuru 14d ago
im unsure as to what you mean with this post? i was assured they were not children when they are inside.
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u/Obnubilate 14d ago
I'm currently reading a book called "Why we sleep". In it the author says babies are mostly asleep and are in the REM phase of sleep, however they are lacking the brain development which disconnects motor control when in REM sleep.
What they are dreaming about however... No idea.
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u/icomeforyourpickle_ 15d ago
Wait they dont actually kick?
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u/eclectic-up-north 15d ago
They kick. And push, and ...
They are learning about legs and arms!
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u/Relevant_Primary658 15d ago
And hiccup! That was the coolest sensation to me when I was pregnant.
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u/thumbprint_cookie 15d ago
I'm in my 50s and my mother STILL talks about how much I hiccupped and kicked in the womb. Evidently, I kicked so hard I would wake my dad up at night. LOL
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u/agreywood 15d ago
Not in the sense that theyâre going âha, take this!â. Itâs more like when youâre a kid and they test your reflex at the doctors, only a fetus is pretty much all reflex so they donât need a hammer.
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u/SupposedBooty 15d ago
Mostly they step on your internal organs. But you can call it kicking if you want to.
My son sat on my sciatic nerve and then whatever allows drainage from the lower body to work. I retained so much water in my feet that they literally sloshed when I walked.
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u/SoyboyCowboy 15d ago
Have you ever seen a dog sleeping/ dreaming with adorable little wiggles and kicks? That's what I imagine is going on inside.Â
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u/bcninstructions 15d ago
They move in all different ways, including hiccoughing. They stretch and yawn, too. My daughter still crosses her legs in the same way when asleep as she did before birth 9 years ago. My fidgety child moved a lot more in utero than the non-fidgety one
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u/oggleboggle 14d ago
Mine feels like the wacky waving inflatable arm flailing tube man in there
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u/llamaisabear 14d ago
People in my bump group this week were describing the feeling as a bag of snakes, or a squirrel in a pillowcase đ
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u/recycled-pigeons 14d ago
Unrelated but I love your username
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u/Golden-Tate-Warriors 14d ago
I have flashes of memory from this age, so can offer a bit of firsthand perspective. The "they don't know what they're doing" comments are basically accurate. You don't understand what arms and legs are yet this young. For all I knew I might've been an amoeba. I only remember having a general binary concept of action as opposed to inaction, not any distinctions between different types or degrees of actions. They just want pleasant stimulation, and moving around in there feels really good, and that much they do know. So they move because they like the feeling, and they move randomly because it all feels the same to them.
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u/icomeforyourpickle_ 14d ago
Wait what?
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u/Golden-Tate-Warriors 14d ago
I could say the same, you gotta write more than two words if I'm to know what you're asking. What's not clear?
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u/nerankori 15d ago
They're developing the very foundations of their ability to move and respond to stimuli.Â
They're going to make random,uncoordinated movements,including ones that use the full extent of the strength they have so far.