Anencephaly is the absence of a large part of the brain and the skull.

Aprosencephaly with open cranium

Anencephaly is one of the most common neural tube defects. Neural tube defects are birth defects that affect the tissue that grows into the spinal cord and brain.

Anencephaly occurs early in the development of an unborn baby. It results when the upper part of the neural tube fails to close. Why this happens is not known. Possible causes include environmental toxins and low intake of folic acid by the mother during pregnancy.

Anencephaly occurs in about 1 out of 10,000 births. The exact number is unknown, because many of these pregnancies result in miscarriage. Having one infant with this condition increases the risk of having another child with neural tube defects.

Images

Ultrasound, normal fetus - ventricles of brain

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Anencephaly Symptoms

Review Date: 05/01/2011
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)