How Many Bones Does A Baby Have?

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You’ll be surprised about how many bones does a baby has.

If you have never wondered, “How many bones does a baby have?”, don’t worry. You’re not alone. It seems like a question best suited for a tricky trivia contest.

Most of us would assume, if asked, that babies have the same number of bones as adults. Some of us would know that the plates in a baby’s skull have not fused so, technically, their skull has more bones than an adult. But few people know that babies have more bones than adults.

Yes, you read that right, babies have more bones than adults.

Way more. Let me explain.

How Many Bones Does A Baby Have?

At birth, a baby has 300 bones, which is almost 100 more bones than an adult. In order to grow in the confined space of the womb and to make the journey through the birth canal, a baby’s bones are softer and are more like a series of bones which later fuse together.


How Many Bones Do Babies Have At Birth?

You may already know that an adult has 206 bones, but we are actually born with 300 bones (1).

How is this possible? Shouldn’t a baby have the same number of bones as an adult?

Or maybe a baby would be born with fewer bones than an adult. They have less hair and fewer teeth, so why not fewer bones?

Why Do Babies Have More Bones Than Adults?

Our skeleton does not start out as the hard, rigid set of bones we have as an adult. Instead, they start life as softer cartilage.

In the womb, babies have a limited amount of space to grow. They also need to be flexible in order to pass through the birth canal. So, at birth, many of a baby’s bones are still predominantly cartilage (2).

As we grow, these smaller, softer cartilage bones harden and fuse together, resulting in the 206 bones we have as an adult.

A good example of this is a baby’s skull. At birth, the skull is made up of five different plates of bone. These plates are formed from softer cartilage and with good reason.

During birth, a baby is pushed down the birth canal by strong muscular contractions. If the skull was the solid, hardened bone we have as adults, the contractions could crush the skull, causing irreparable damage.

Instead, the five soft plates can be squeezed and overlap, allowing the baby’s head to emerge without damage (3).

This is why you can feel the soft spots at the top and back of a baby’s skull. These soft spots, called fontanelles, will slowly grow together and harden, closing fully between 7 and 18 months.

What Extra Bones Do Babies Have?

Babies have 300 bones, but these are bones that have not yet fused or fully formed.

Using the example of the skull once more, the five plates of bone that fuse are pieces of a single bone. So babies do not have extra bones. They have the bones of an adult, but those bones are in pieces.

When Do Babies Bones Harden After Birth?

Because hardened bone cannot grow, the ends of our bones are formed with softer growth plates of cartilage. This way, our bones can lengthen and continue to support and protect our bodies as we grow.

These growth plates at the end of the bone finally harden somewhere between the ages of 20 and 25. After this point, our bones can no longer grow.

The clearest example of this is the fontanelle of the skull. Your baby’s bones are slowly hardening from the moment they are born.

However, this malleability and slow hardening come with problems. Your child’s bones can become misshapen if they are confined by something such as tight shoes as they grow.

This malleability can also be positive if your child is born with a misshapen bone. It is possible, to some degree, to direct the growth of that bone into a more regular shape as they grow.

At What Age Do You Have 206 Bones?

The exact age at which you have 206 bones varies from person to person, but this normally happens by early adulthood or around 20 to 25 years.

By this time, the cartilage growth plates at the ends of the bones have hardened, and your bones no longer grow.

However, although your bones do not grow in size, your body slowly replaces the materials in your bones. In this way, your bones are completely replaced every 10 years or so.

How to Protect Your Baby’s Bones

Once your baby is born, the best thing you can do for their skeletal system is to ensure they eat well and have good, balanced nutrition.

One of the most important vitamins for bone health is vitamin D. Babies who are fed with formula usually receive enough vitamin D.

Take Note

However, babies who are exclusively breastfed, or have a combination of breast milk and formula, may need a vitamin D supplement (4). This is true even if the baby’s mother is taking a vitamin D supplement themselves. Getting your baby a few minutes of sunlight per day may help avoid the need for a supplement.

Once your baby begins to eat solid food, they will need a diet with plenty of vitamin D and calcium. Calcium is the main mineral in bone, and plentiful calcium deposits when you are a child ensures strong bones when you are grown.

Calcium-rich foods include:

  • Dairy products.
  • Some fish, such as sardines, salmon, and trout.
  • Green vegetables like spinach, kale, okra, and collards.

Vitamin D rich foods include:

  • Fatty fish such as mackerel, salmon, and tuna. Be careful about how much fish you give your child because of potentially high mercury levels (5).
  • Egg yolks.
  • Beef liver.
  • Vitamin D enriched foods.

In addition to feeding your child’s bones, you can help strengthen them by encouraging your child to take part in weight-bearing exercise. Activities such as running, jumping, and climbing put weight on the bone, which helps the body build stronger bones.


Boning Up on Your Baby’s Anatomy

Your baby is not only the most beautiful child in the world, but they are also an amazing collection of soft, springy bones that will harden and fuse over time to create a strong, sturdy adult skeleton.

You can help this process by encouraging good nutrition and weight-bearing exercise which together will set your child up for a lifetime of strength.

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About the Author

Patricia Barnes

Patricia Barnes is a homeschooling mom of 5 who has been featured on Global TV, quoted in Parents magazine, and writes for a variety of websites and publications. Doing her best to keep it together in a life of constant chaos, Patti would describe herself as an eclectic mess maker, lousy crafter, book lover, autism mom, and insomniac.
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