Sure, babies are adorable and have this irresistible smell that compels us to sniff them daily, but those tiny new humans who cause grownups to talk in reeeeallly high voices (more on that below) are also pretty darn weird. Like, did you know babies are born without kneecaps? How about the fact that if you look in your newborn’s eyes for long enough, your heartbeats will sync up? If you think that‘s strange, see what else made our list of surprising, little-known baby facts.

Babies learn their mother’s voice in the womb

It makes sense that newborns would know their mothers’ voices—they’ve just spent 9 months shacked up inside Mom’s body. In fact, studies show that not only do babies know her voice, but they prefer it, consistently showing increased attention when exposed to mom’s sound versus dad’s. Want proof? Just watch this adorable TikTok video of a wailing newborn calming down after hearing the familiar sound of Mom’s voice.

They also remember music they heard in utero

If you were on a disco music kick throughout your pregnancy, don’t be surprised if your baby perks up at the sound of “Saturday Night Fever.” A study by the University of Helsinki found that babies who were exposed to a particular lullaby in the womb appeared to recognize the song even several months after birth. So pick your tunes wisely!

Related: Study Finds Babies Love Concerts Just As Much As You Do

Newborns can’t taste salt but have way more taste buds than adults

No matter how many chips you eat during those early days of breastfeeding, it won’t matter to your tiny guzzler. Research suggests that your baby can’t taste salt until about 4 months of age. That being said, your budding foodie has about twice the number of taste buds as you—including having them in the tonsils as well as the roof and sides of the mouth. Scientists think these added taste buds help make babies more receptive to their mothers’ milk.

Babies are born without kneecaps (kinda)

Those cute little baby knees are extra pudgy for a reason: there are no kneecaps in there! Or rather, infants don’t have hard kneecaps made of bone. Baby knees are initially only soft cartilage (better for cushioning them during tumbles), which eventually ossifies into bone as your tot grows.

And yet, at birth they have more bones than adults

Those little skeletons aren’t exactly miniature copies of ours. Most babies are born with almost 100 more bones than grownups—about 300 altogether—which fuse as they grow, eventually becoming the standard 206 bones that are typically found in adults.

Newborns can’t cry with tears

Oh, but they can cry. It’s just… tearless. This is because a baby’s tear ducts don’t fully develop until anywhere from 2 to 12 weeks of age.

Some babies have a “mini-period” after birth

Don’t freak out if you see a little pink or red discharge in your baby girl’s diaper. This phenomenon, called “pseudo-menstruation” or “false menses,” can occur in a small percentage of newborn girls up to 10 days after birth and is caused by the rapid decrease in estrogen that occurs when a babe leaves the womb. It shouldn’t last more than a few days.  Want more info? This article lays it all out.

Some may also have breasts—or even lactate!

There’s nothing new about babies lactating (about 5% do it), though luckily we’ve stopped thinking of it as “witch’s milk.” Once again, this is thanks to the estrogen in Mom’s body and can happen to boys and girls. No need to worry unless it doesn’t go away within a few weeks of birth (though breastfed babies may have breast swelling that can last up to six months, according to Seattle Children’s Hospital).

Babies have more brain neurons than adults

There’s a lot of growing to do in that promising little brain, and babies are pretty much born with all the neurons they’ll have for their entire lives. Since a good amount of brain cells die as we age, this means newborns actually have more neurons than we grownups do.  As your baby grows, these nerve cells are trimmed according to aging and the old “use it or lose it” adage.

And their brains double in size during the first year

It might seem like your baby has a big head when she pops out into the world, but that newborn noggin will grow to twice its size during the first year! This translates to about an inch during the first month and a half-inch every month thereafter, according to Mayo Clinic.

Related: 13 Baby Myths Parents Can Officially Stop Worrying About

Our exaggerated “baby talk” actually helps babies learn

The particular way we speak to babies isn’t random (studies show it’s the same all over the world with even Rhesus monkeys addressing their littles in higher pitches). According to a University of Florida study, that strange but familiar way we talk to babies—higher pitch, slower speed, exaggerated pronunciation—actually helps them learn how the words should sound coming out of their mouths.

Related: The Annoying Way to Talk to Babies That Actually Benefits Them

Baby stomachs are the size of a walnut

Turns out there’s a reason babies get full so quickly—and why you have to feed them so often! A newborn baby’s stomach is about the size of a walnut and can hold just 4-5 teaspoons at a time. Any more than that and you’d better hope you’ve got a burp cloth on your shoulder for the overflow.

You are probably addicted to your baby’s smell

Can’t get enough of your newborn’s personal perfume? It’s not just you. According to a study from the University of Montreal, a baby’s smell is as addictive as drugs are to addicts. The study found that the newborn baby’s odor activated the feel-good reward centers in adult brains, similar to those activated when an addict does drugs. And for moms, this rush of dopamine was even more heightened. So breathe it in, parents!

If mom and baby look into each other’s eyes for long enough, their heartbeats sync up

This is how connected moms and their babies are and, unlike a newborn, we could actually shed a tear it’s so sweet. Research shows that moms and babies are so in tune with one another that if they focus on each other intently, their hearts beat in sync. Think that’s cool? A 2017 study also found that when adults and babies look at each other, their brain waves synchronize. Scientists think this neural connection helps facilitate babies’ social learning. We’re weeping.

Babies are born with an innate sense of rhythm

Your baby may not have any moves yet, but she’s got the beat! Infants are born with a natural rhythm recognition that allows them to detect missing beats in drum sequences they hear, according to a study by the Institute for Psychology in Budapest. Scientists believe it is a result of spending so much time so close to the “ba-bum, ba-bum, ba-bum” of Mom’s beating heart while they’re in utero.

Now go cuddle your loveable little weirdo. And if you’re still in the mood for some quirk, here are 10 weird (but normal) things that babies do.

Make sure to capture all the cutest moments with your babe—and share them with your family and friends near and far—with the Tinybeans app. The secure platform puts parents in total control of who sees and interacts with photos and videos of their kids.

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