Anencephaly is a serious birth defect in which a baby is born without parts of the brain and skull. It is a type of neural tube defect (NTD). These are birth defects that happen during the first month of pregnancy, usually before a woman knows she is pregnant. As the neural tube forms and closes, it helps form the baby’s brain and skull (upper part of the neural tube), spinal cord, and back bones (lower part of the neural tube).
Anencephaly happens if the upper part of the neural tube does not close all the way. This often results in a baby being born without the front part of the brain (forebrain) and the thinking and coordinating part of the brain (cerebrum). The remaining parts of the brain are often not covered by bone or skin.
Almost all babies born with anencephaly will die shortly after birth. CDC estimates that each year, about 1 in every 4,859 babies in the United States will be born with anencephaly