4 st week of pregnancy: closure of the neural tube

At this embryological stage, the neural tube, the nerve groove at the back of the embryo, closes.   It will give birth to the brain and the spinal cord. To limit any defect in the closure of this neural tube that could lead to spina bifida, you may have started folic acid supplementation during the preconception or early pregnancy.

The heart begins to beat and the structures necessary for the formation of the eyes and ears develop. Small buds on the top of your embryo appear, which will become your baby's arms.