Fetal development four weeks after conception
By the end of the sixth week of pregnancy, or four weeks after conception, small buds appear that will become arms.
The sixth week of pregnancy, or four weeks after conception, the neural tube along your baby's back is closing. The brain and spinal cord develop from the neural tube. The heart and other organs also start to form.
Structures needed to form the eyes and ears develop. Small buds appear that will soon become arms. Your baby's body begins to take on a C-shaped curve.