8 weeks and 4 days pregnant

In the upper limb buds, the flat expansion that will form the hand can be identified. The fingers are becoming more distinct and there will now be the first signs of movement at the elbows.

Your baby’s bones are beginning to develop – and they will continue to lengthen from now until his teenage years.

You won’t be aware of your developing baby’s activities inside the uterus for some months yet, but the fact that his elbows are forming allows him to make some small movements; the wrists do not yet move.

Your baby is looking more human by the day. His vertebrae and ribs are now in place, and his fingers are gradually lengthening. His body is less curled up than it was a few weeks ago.

The skeleton will gradually calcify and harden. With the exception of the cranial skull bones, all your baby’s bones have a soft cartilage core that will later be reabsorbed as it is converted into hard bone. This process of hardening, known as ossification, starts in so-called primary ossification centres during the next five weeks of your pregnancy. Within these primary centres, specialized cells form spongy then hard bone as calcium salts are laid down. Within the hard bone is red bone marrow, which in later weeks will become the main producer of the baby’s red blood cells.

Secondary ossification centres develop in the second trimester at the ends of each of your baby’s bones.