By 7 weeks, the embryo has grown to about 10mm long from head to bottom. This measurement is called the crown-rump length.
The brain is growing rapidly and this results in the head growing faster than the rest of the body. The embryo has a large forehead, and the eyes and ears continue to develop.
The inner ears start to develop, but the outer ears on the sides of the head will not appear for a couple more weeks.
The limb buds start to form cartilage, which will develop into the bones of the legs and arms. The arm buds get longer and the ends flatten out – these will become the hands.
Nerve cells continue to multiply and develop as the brain and spinal cord (the nervous system) starts to take shape.