Anencephaly is a severe birth defect defined by the absence of a major portion of the brain, skull, and scalp. As a neural tube defect, it is considered a fatal condition that develops very early in pregnancy. This condition results in the lack of structures necessary for consciousness and long-term survival. Understanding the nature of anencephaly and focusing on comfort-centered care can provide guidance for families facing this serious diagnosis.
Understanding Anencephaly: Origin and Diagnosis
Anencephaly is a neural tube defect (NTD) that occurs when the rostral, or head, end of the neural tube fails to close completely during embryonic development. This failure happens between the 23rd and 26th day following conception, often before pregnancy is confirmed. Consequently, the forebrain and cerebrum do not develop, and the remaining exposed brain tissue degenerates due to exposure to amniotic fluid.
The cause of anencephaly is multifactorial, involving a complex interplay between genetic predisposition and environmental factors. Factors that increase the chance of this defect include low levels of folate (Vitamin B9) during early pregnancy and maternal health conditions like uncontrolled diabetes. Taking anti-seizure medications can also elevate the risk.
Anencephaly is frequently detected during routine prenatal screening, often in the second trimester. A blood test known as the maternal serum alpha-fetoprotein (MSAFP) screening may show elevated levels of alpha-fetoprotein. If the screening is positive, a detailed ultrasound is performed, which reveals the characteristic absence of the skull and major brain structures. An amniocentesis may also be performed to test a sample of amniotic fluid, sometimes checking for accompanying chromosomal abnormalities.
The Prognosis: Addressing Life Expectancy
Long-term survival is impossible because the severe malformation prevents the development of brain structures needed for autonomous regulation. The cerebrum, responsible for consciousness and coordination, is missing or severely underdeveloped. Although a baby with anencephaly may have a functioning brainstem controlling basic reflexes like breathing and heart rate, the absence of the higher brain makes the condition lethal.
The majority of affected pregnancies end in miscarriage or stillbirth before the delivery date. For infants born alive, the life expectancy is extremely short, measured in minutes, hours, or days. Most infants born with anencephaly die shortly after birth.
A small percentage of liveborn infants may survive for a short time; some studies show that over 40% survive longer than 24 hours. However, survival beyond a week is rare, estimated to occur in only about 5% of liveborn cases. These infants are generally unconscious and cannot see, hear, or feel pain, though they may exhibit reflexive movements controlled by the intact brainstem.
Palliative Care and Comfort Measures
Following a diagnosis of anencephaly, medical care shifts from curative treatment to providing compassionate, supportive, or palliative care. The goal is to maximize the infant’s comfort and dignity while providing the family with emotional support during their brief time together. This approach involves specialized teams, including neonatal palliative care and hospice services, which assist with planning before and after birth.
Palliative care decisions often begin prenatally, including discussions about the preferred location and method of delivery. The care plan aims to avoid medical interventions that would be futile or prolong suffering. Life support measures, such as mechanical ventilation or surgically placed feeding tubes, are typically avoided because they do not change the ultimate outcome.
After birth, comfort measures are prioritized to ensure the baby is warm and secure. Gentle handling and swaddling are important elements of this care, along with addressing any signs of discomfort. Pain control, hydration, and nutritional support focus purely on comfort rather than sustaining life. The care team supports the family in creating memories, such as holding the baby, taking photos, and spending time together.
Prevention and Recurrence Risk
While the cause of anencephaly is complex, the most effective known preventive measure is consistent folic acid supplementation. Individuals who could become pregnant should take 400 micrograms (mcg) of folic acid daily, beginning before conception. This regimen should continue through the first trimester of pregnancy, as the neural tube closes very early.
For families who have already had a child with anencephaly, the risk of recurrence in a subsequent pregnancy is higher than in the general population. Because this increased risk can range from 2% to 10%, consultation with a genetic counselor is recommended. A medical provider may prescribe a higher dose of folic acid, often 4 milligrams (mg) daily, to reduce the chance of another neural tube defect.