Bone Development in Babies

The human body has 206 bones that help us move. Babies start developing bones during the second trimester and continue developing for years after birth. Keeping babies healthy during bone growth and development ensures a strong skeletal system for life.

Time Frame

• According to the Mayo Clinic, a baby's bones begin forming around week 15 after conception. Before week 15, bones are composed of cartilage and connective tissue then begin the process of ossification, or forming into bones. These bones are visible during ultrasounds, which allow doctors to determine if there are any existing problems with the skeletal system before birth.

Significance

• A baby's bone structure is fully formed by week 29 of fetal development. Disney Family says that a baby's bones will continue to grow for the rest of pregnancy and also through adulthood. Bones adjust to the body's growth and to fractures and breaks a child might endure during childhood.

Bone Count

• At birth, a baby has about 300 bones that eventually fuse and grow together to create the 206 bones found in the adult body. Kids Health indicates that some of a baby's bones are made of soft, flexible cartilage, allowing her to be less prone to bone breaks when learning how to roll over, crawl and walk. This explains the common saying that babies are made of rubber.

Skull Formation

• Babies are born with spaces, or cranial sutures, in their skull, which allows the head to mold during birth for an easier delivery. According to Health Central, these spaces allow a baby's head to shift into an oblong shape caused from the pressure of a head-first vaginal birth. The gaps in the skull also accommodate fluid that may collect under the baby's scalp during birth and allow the brain to grow. The spaces will eventually fuse together within a couple weeks, creating a complete skull.

Calcium

• As a baby grows her bones begin to calcify with the addition of vitamin D and calcium that she receives from her mother's milk or through infant formula then later through milk. Older babies may experience growing pains as bones begin to grow and adjust, caused by muscles trying to catch up to the quickly growing bones.