By 8 weeks, your baby has leg buds that look like flippers.

When you're between 5 and 6 weeks pregnant, your baby sprouts paddle-like buds that will lengthen and grow into arms. The fontanel on the back of the head usually closes by the time your baby is around 4 months old the one on top typically doesn't close until after your baby's first birthday. Within a few days, though, the bones rearrange themselves and the skull goes back to a dome-like shape. This is why many newborns have distinctly pointy heads right after they're born. You'll be able to feel the soft spots between the bones, called fontanels, on the top and back of your newborn's head.ĭuring birth, the softness of the skull bones and the loose connections between them allow the skull to be gently compressed into a bullet-like shape that more easily fits through the birth canal. It starts out as separate bones joined by flexible tissue.

Your baby's skull isn't one large bone, like an adult's. Then, calcium and phosphate – minerals stored in your body and replenished by the foods you eat – are added to the tissue to harden it. At about 10 weeks, bone tissue starts to form as cartilage or membrane. All bones develop in the same way in a process called ossification.

Flat bones of the skull develop from