Short answer · Medically reviewed summary · Last updated: 2026-05-08
Anencephaly is a serious neural tube defect that occurs when the upper part of the neural tube fails to close during the first few weeks of embryonic development, resulting in the absence of a major portion of the brain and skull. Because this condition is always fatal, management focuses on compassionate palliative care and emotional support for the family during and after pregnancy. What causes Anencephaly? Anencephaly occurs during the first 28 days after conception.
What is Anencephaly
What is Anencephaly? Plain-language, medically reviewed definition plus the lived reality told by patients.
Anencephaly is a serious neural tube defect that occurs when the upper part of the neural tube fails to close during the first few weeks of embryonic development, resulting in the absence of a major portion of the brain and skull. Because this condition is always fatal, management focuses on compassionate palliative care and emotional support for the family during and after pregnancy.
What causes Anencephaly?
Anencephaly occurs during the first 28 days after conception. The exact cause is usually a combination of genetic and environmental factors. It is a type of neural tube defect (NTD). While the specific trigger is often unknown, research suggests that low levels of folic acid in the mother’s system, maternal diabetes, and certain medications can increase the risk of a pregnancy being affected by Anencephaly.
Which body systems are affected by Anencephaly?
Anencephaly primarily affects the central nervous system and the skeletal structure of the head. Because the neural tube does not close properly, the brain's forebrain and cerebrum—the areas responsible for thinking and coordination—often do not develop. Additionally, the protective bone covering (skull) is missing. As a result, the body's ability to regulate vital functions like breathing and heart rate is severely compromised from birth.
How common is Anencephaly?
According to the Centers for Disease Control and Prevention (CDC), Anencephaly affects approximately 1 in every 4,600 babies born in the United States each year. It is more frequently diagnosed in female infants than in male infants. Because 31 people in the DiseaseMaps.org community have shared their experiences with this condition, we know that families often face unique grief and diagnostic journeys that are best navigated with specialized support.
Key facts about the diagnosis of Anencephaly
- Prenatal Detection: Most cases are identified via routine ultrasound during the first or second trimester.
- Prognosis: The condition is not correctable; unfortunately, Anencephaly is always fatal.
- Survival: While most infants pass away before or shortly after birth, survival time varies from minutes to, in extremely rare cases, several days.
Next steps
- Consult with a high-risk obstetrician or a maternal-fetal medicine specialist for detailed guidance.
- Seek support from bereavement counselors or specialized support groups to process the emotional impact of an Anencephaly diagnosis.
- Visit DiseaseMaps.org to connect with others who have navigated similar experiences in our global community.
Medical disclaimer: This information is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment.
References
- NIH Genetic and Rare Diseases Information Center (GARD): Anencephaly.
- Orphanet: Neural tube defects.
- Centers for Disease Control and Prevention (CDC): Facts about Anencephaly.
- OMIM (Online Mendelian Inheritance in Man): Anencephaly entry.
