5. Missing rear, side, and front skull bones
Defects of the neural tube such as Anencephaly are passed to the fetus through the genes of both parents. The defect can also be a result of environmental factors. Though Anencephaly may be suspected as a result of blood screens or amniotic testing, it can also be confirmed visually through ultrasound or at birth.
Every instance of Anencephaly results in the lack of formation of the skull in the back of the head. In some cases, the sides and front of the skull also fail to develop. This leaves the brain without protection and in most cases, the child will not survive the birthing process.
In cases where there is some bone formation, the skull is not fully formed or may have large obvious holes in the surface. Missing skull bones can be seen in ultrasounds starting from the third month of pregnancy. Anencephaly is always visually notable at birth due to the lack of bones on the skull.