6 Reasons Why Babies Have More Bones than Adults

Did you know that babies have more bones than adults? The reasons for this range from adaptability to protection. Learn more.
6 Reasons Why Babies Have More Bones than Adults
Maria del Carmen Hernandez

Written and verified by the dermatologist Maria del Carmen Hernandez.

Last update: 01 May, 2024

It may be hard to imagine, but newborn babies have about 300 bones in their tiny bodies. As they grow and develop, so do their bones, and by the time they reach adulthood, their bones will be limited to about 206. Do you know why babies have more bones than adults?

In this article, we’ll explore the reasons for this phenomenon and how it can benefit your baby’s growth and development.

Why do babies have more bones than adults?

While babies may appear fragile and delicate, they have more bones than adults. In addition to contributing to development, this may also happen for the following reasons.

1. Incomplete ossification

Ossification, which is part of the bone development process, begins around the eighth week of pregnancy. However, the bones of newborns are made primarily of cartilage, which, while rigid, is also more flexible and malleable than adult bones.

As the child grows, much of that cartilage calcifies and gives rise to bones. A recent study published in StatPearls suggests that many of these bones fuse together in the first few months, reducing their number to 206.

Also, the organization KidsHealth organization explains that the vast majority of bones in children’s hands and feet are made of cartilage. For this reason, they can’t be seen on X-rays. Over time, these cartilages ossify and become bones.

2. Facilitating birth

A baby’s skull is made up of several bones separated by fontanelles and sutures. These cavities allow the skull to reduce its size to pass through the birth canal without injuring nerve structures.

You may be interested in: 13 Curious Facts About Newborns

3. Promoting healthy baby growth

As we know, babies are meant to grow and develop into healthy adults. Therefore, the presence of more bones during the first years of life helps the skeleton to have enough material for muscle development and proper bone growth.

In addition, babies experience a growth spurt during the first years of life. So, additional bones are a necessary adaptation to promote this rapid development and provide adequate structural support.

According to an article published in the journal Pregnancy Birth & Baby, the fontanelles located in the skull allow the brain to grow, expand, and finish settling in. After a few months, the skull bones fuse, and these cavities close.

4. Increased blood cell production

Babies require a continuous production of blood cells for growth and development. With more bones, they have a greater capacity for blood cell production in the bone marrow, which is essential for maintaining a healthy circulatory system.

In fact, until week 21, the spleen and liver are responsible for producing blood cells. However, according to Children’s Health Network, in the third trimester and after birth, the bone marrow becomes the main site of production.

5. Bone plasticity

Bone plasticity refers to the ability of bones to remodel and adapt in response to the pressures and forces exerted on them. Babies have more plastic bones, which allows them to adapt and grow quickly as they develop motor skills and learn to move.

Unlike adult bones, children’s bones have more cartilage and water because they’re constantly forming and their outer layer (periosteum) is stronger and thicker. Because of this, they heal faster and are more flexible and elastic.

Also, The Royal Children’s Hospital Melbourne explains that juvenile bone is also more porous than adult bone, which gives it the ability to bend even more.

6. Contribution to the development of the respiratory system

Babies depend on a developing respiratory system to get the oxygen they need. The additional bones in the chest and rib cage provide flexibility and additional space for lung growth and expansion.

This more flexible skeletal structure allows for greater lung capacity, which facilitates proper breathing during the critical period of lung development in infancy. That is, during the first 3 years of a child’s life, the lungs continue to develop and mature into an adult lung, increasing the amount of surface area they require.

At what age does the number of bones decrease?

From the time they’re born, infants show fragility and delicacy. However, they have more bones than adults.

Although bones grow and develop from infancy to adolescence, they have a period of rapid growth from birth to two years of age, which resumes at puberty. The process isn’t complete until the mid-20s.

The benefits of having more bones than adults

Babies have more bones than adults because of their need to adapt to rapid growth and development. These bones provide flexibility, protection, and physical adaptability and also play a key role in the development of the nervous system and preparation for future growth.

As babies grow, many of these bones will fuse together, forming the adult bone structure. Understanding these aspects allows us to appreciate the amazing ability of the human body to adapt and grow from an early age.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.