Michael S. Porter
Eric C. Nordby
Receiving a diagnosis of anencephaly during pregnancy is one of the most difficult experiences a family can face. This severe birth defect affects the development of a baby’s brain and skull, and understanding what it means can help parents navigate an unimaginably painful time. At nybirthinjury.com, we provide clear, medically accurate information to support families through these challenging moments, helping them understand the condition, what to expect, and where to turn for compassionate care and support.
What is Anencephaly?
Anencephaly is a serious birth defect in which a baby is born missing large portions of the brain, skull, and scalp. It belongs to a group of conditions known as neural tube defects, which occur when the neural tube (the early structure that forms the brain and spinal cord) does not develop properly during the first few weeks of pregnancy.
In anencephaly, the upper part of the neural tube fails to close completely during the first month after conception. This prevents normal development of the forebrain and cerebrum, the parts of the brain responsible for thinking, coordination, and consciousness. As a result, these critical brain structures either do not form at all or remain severely underdeveloped. The bones of the skull that would normally cover and protect the brain also fail to form properly.
This condition is always fatal. There is no cure or treatment that can restore the missing brain tissue. Most babies with anencephaly are stillborn, and those who survive birth typically live only hours or days.
What Causes Anencephaly?
The exact cause of anencephaly is not fully understood, but research has shown that it results from a combination of genetic and environmental factors working together during the earliest weeks of pregnancy, often before a woman knows she is pregnant.
Several risk factors have been identified:
Folate deficiency. Low levels of folic acid (vitamin B9) before and during early pregnancy significantly increase the risk of neural tube defects. Folate plays an essential role in cell division and DNA formation, processes that are critical during the rapid development of the neural tube.
Maternal diabetes. Poorly controlled blood sugar levels in early pregnancy increase the risk of several birth defects, including anencephaly.
Certain medications. Some anti-seizure medications and other drugs known to interfere with fetal development (teratogens) can raise the risk when taken during early pregnancy.
Maternal fever or hyperthermia. Episodes of high fever or prolonged exposure to heat sources such as hot tubs during the first trimester may contribute to neural tube defects.
Genetic factors. Specific gene mutations and chromosomal abnormalities can increase susceptibility. Families who have had one pregnancy affected by anencephaly face a higher risk in future pregnancies.
It is important to emphasize that anencephaly is not caused by anything the mother did or failed to do. These factors increase risk, but in most cases, no specific cause can be identified for an individual pregnancy.
Can Anencephaly Be Prevented?
While not all cases can be prevented, taking folic acid before and during early pregnancy is the single most effective way to reduce the risk of anencephaly and other neural tube defects.
Healthcare guidelines recommend that all women of childbearing age take 400 micrograms of folic acid daily, even if they are not planning to become pregnant. Because the neural tube closes so early in pregnancy (by about the fourth week after conception), it is critical that folate levels are adequate before pregnancy begins.
Women who have previously had a pregnancy affected by a neural tube defect should speak with their healthcare provider about taking a higher dose, typically 4,000 micrograms (4 milligrams) daily, starting before conception.
Many countries, including the United States, have implemented folic acid fortification programs, adding the vitamin to grain products such as bread, pasta, and cereal. These programs have contributed to significant reductions in the rates of neural tube defects since their introduction.
How is Anencephaly Diagnosed?
Anencephaly is often detected during routine prenatal care, either through ultrasound or blood screening tests.
Prenatal screening. A blood test known as maternal serum alpha-fetoprotein (AFP) screening, typically done between 15 and 20 weeks of pregnancy, can identify elevated AFP levels, which may indicate a neural tube defect. If levels are abnormal, further testing is recommended.
Ultrasound. A detailed ultrasound can reveal the physical characteristics of anencephaly, including the absence of skull bones and brain tissue. Most cases are identified through ultrasound in the second trimester.
Amniocentesis. In some cases, a sample of amniotic fluid may be tested to confirm the diagnosis or evaluate for associated genetic conditions.
At birth, anencephaly is immediately apparent due to the unmistakable physical features of the condition.
What Does Anencephaly Look Like?
The physical signs of anencephaly are distinct and visible at birth. They include:
- Missing bones at the top and sides of the skull
- Exposed or absent brain tissue, with no covering of scalp or bone
- A small, flattened head shape
- Absence of the forebrain and cerebrum, the largest parts of the brain
Some babies with anencephaly may also have other birth defects, such as cleft palate or heart abnormalities.
Babies with anencephaly are not believed to experience awareness or pain in the way typical newborns do, because the parts of the brain responsible for consciousness and sensation are absent or severely underdeveloped.
Medical Care and What to Expect
Anencephaly is incompatible with life. The absence of essential brain structures means that babies born with this condition cannot survive long term. Most affected pregnancies end in stillbirth, and babies who are born alive typically live only a few hours or days.
There is no treatment that can cure or correct anencephaly. Medical care focuses on providing comfort and supporting the family through an incredibly difficult time.
Some families may choose comfort care measures, which prioritize keeping the baby warm, providing comfort-focused nutrition if possible, and allowing time for family members to hold and spend time with their child. Others may choose more intensive support measures, though these do not change the outcome.
Healthcare teams, including neonatal specialists and palliative care providers, work closely with families to ensure care aligns with their values and wishes.
How Common is Anencephaly?
Anencephaly affects approximately 1 in every 5,250 births in the United States, according to the Centers for Disease Control and Prevention (CDC). Globally, rates vary depending on factors such as folic acid supplementation programs, genetic background, and regional dietary practices.
Neural tube defects, including anencephaly, are among the most common types of serious birth defects. In the United States, it is estimated that about 3,000 pregnancies each year are affected by neural tube defects, though many of these are diagnosed prenatally.
The introduction of folic acid fortification and increased awareness of prenatal vitamins have contributed to declines in anencephaly rates in many parts of the world.
Support and Resources for Families
Families facing a diagnosis of anencephaly need compassionate, specialized care that addresses both the medical and emotional aspects of their experience. This is not a journey any parent should navigate alone.
In New York, several leading hospitals offer multidisciplinary support for families dealing with anencephaly and other severe prenatal diagnoses. These include:
NewYork-Presbyterian Hospital. The Carmen and John Thain Center for Prenatal Pediatrics provides counseling, care coordination, and parent-to-parent connections for families facing complex fetal diagnoses.
Mount Sinai, NYU Langone, and Columbia Presbyterian. These medical centers offer perinatal palliative care programs that help families make informed decisions, plan for birth, and receive bereavement support.
Albany Medical Center. Specialized neonatal and maternal-fetal medicine teams provide compassionate care throughout pregnancy and after delivery.
Many hospitals also connect families with grief counselors, social workers, chaplains, and support groups. These resources can help parents process their emotions, make decisions that feel right for them, and find community with others who have faced similar losses.
National organizations such as the March of Dimes and local bereavement support groups offer additional guidance and connection.
Moving Forward with Support
Learning that your baby has anencephaly is devastating. There are no words that can ease the pain, and no single path forward that is right for every family. What matters most is that you have access to accurate information, compassionate medical care, and emotional support as you make decisions that honor your values and your baby.
Whether you choose to continue the pregnancy or make other decisions, you deserve to be supported with dignity, respect, and understanding. Reaching out to trusted healthcare providers, counselors, and support networks can help you find the care and guidance you need during this profoundly difficult time.