How Many Bones Do Babies Have? Plus, Why Do Adults Have Fewer?

How Many Bones Are Babies Born With, And Why Do Adults Have Fewer?

April 22, 2020 Updated May 20, 2020

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When you gaze adoringly upon your newborn, you’re probably thinking about how precious their teeny tiny toes are. Or how you could just gobble up their wittle fingers. You may even be marveling over how perfectly round your little pumpkin’s head is. And maybe all of those oh-so-cute bits and baby baubles make you wonder, How many bones does a baby have? Because looking at your newborn, it’s easy to imagine they’re basically just one big squishy lump of pure love. In reality, though, the newborn you’re holding in your arms has even more bones than you do. Curious? You’re not alone. According to the most recent search data, the term “how many bones does a baby have” has a search volume of nearly 10,000 a month! A MONTH! Here’s the scoop on this fascinating topic.

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How many bones do adults have?

Before we reveal the number of bones your baby is born with, it makes sense to give this conversation some context. So, consider this: Adults have 206 bones, accounting for about 15 percent of their body weight.

How many bones does a baby have?

Now, for the good stuff! Drumroll, please… a baby is born with roughly 300 bones in their body. Wait, what?! How could something so tiny contain so many bones? As in, almost 100 more than an adult? We’ll get into that more in a minute. But it merits mentioning that newborns have 176 true bones and the remainder of the roughly 300 are called cartilaginous bones, meaning they have not yet calcified.

Why do babies have more bones than adults?

You now know that babies’ skeletons have 300 parts. What you don’t know yet is why. Well, for starters, if a baby was fully “hardened” at birth, it would render labor and delivery pretty much impossible. Cartilage is soft and flexible, giving baby pliability in the birth canal and as they continue to grow.

As for why there are “extra” bones, the cartilaginous “bones” just haven’t fused together yet. Once they do, they combine to form a greater bone. In other words, many minuscule bone fragments fuse to form a single bone. Say, for example, baby’s skull. You’ve probably been warned a million times not to mess with the “soft spot” on your little one’s dome. These soft spots, known as fontanelles, exist in the space where cartilage hasn’t yet fused into bone. If your baby is born with eight small pieces of bone in their skull, they will eventually reduce to four bones in the skull.

This hardening over time is a process known as endochondral ossification.

At what age do babies’ bones fuse together?

Here’s a fun fact: A baby’s bones won’t fully fuse together while they’re a baby. In fact, the process of ossification and bone growth won’t stop until early adulthood — usually around the age of 25. At this point, you’ll have 206 bones that are as big as they will ever be.

However, this doesn’t mean your bones are just going to kick back and chill from then on. In a process called remodeling, they’ll form new bone tissue and break down older bone into calcium and other minerals to be released into the bloodstream. That part of the process is called resorption. And if you really want your mind to be blown, mull this over: Your skeleton completely regenerates itself every decade or so through remodeling.