The estimated number of bones in a newborn baby is approximately 270. At birth, babies have more bones than adults due to the presence of soft, flexible cartilage in many areas. As they grow, some of these bones will fuse together, resulting in a total of 206 bones in the average adult skeleton. The process of bone fusion begins during early childhood and continues into young adulthood. This developmental process allows for growth and the eventual formation of a stronger, more resilient skeletal structure.