Anencephaly: What It Means, Why It Happens, and How It Can Be Prevented

Quick Answer

Anencephaly is a serious neural tube defect in which a baby's brain and skull do not develop fully in early pregnancy. It is, sadly, a fatal condition with no cure, and most babies do not survive beyond birth. It happens in the first few weeks of pregnancy, usually before a woman even knows she is pregnant, and it is not caused by anything the mother did. The most important thing that lowers the risk in future pregnancies is taking folic acid before conception.

Key Takeaways

• Anencephaly is a neural tube defect where the upper part of the neural tube does not close, so major parts of the brain and skull do not form (CDC).

• It is fatal, and there is no cure or treatment. Almost all babies with anencephaly die shortly after birth. This is painful to read, and we state it gently but honestly so you have accurate information.

• It is not your fault. It is not caused by stress, by something you ate, or by anything you did or did not do.

• Folic acid is the key preventive step. Taking 400 mcg of folic acid before conception and in early pregnancy significantly lowers the risk of neural tube defects.

• If you have had a previously affected pregnancy, a much higher folic acid dose (5 mg) is recommended for future pregnancies, on prescription.

What Is Anencephaly?

Anencephaly is a serious birth defect in which a baby is born without parts of the brain and skull (CDC). It is a type of neural tube defect (NTD).

Very early in pregnancy, a structure called the neural tube forms and then folds and closes. The upper part goes on to form the brain and skull, and the lower part forms the spinal cord and backbone. In anencephaly, the upper part of the neural tube does not close all the way, so the front and thinking parts of the brain, and the bone and skin that would cover them, do not develop.

This all happens in the first few weeks of pregnancy, typically within about the first month after conception, which is often before a woman even knows she is pregnant. That timing is important, and it is one reason this is not something a mother can cause or prevent by anything she does after finding out she is pregnant.

Is Anencephaly Fatal? Understanding the Outcome

This is the hardest part, and we will be honest and gentle. Anencephaly is fatal. There is no known cure or treatment (CDC). Sadly, many pregnancies affected by anencephaly end in miscarriage or stillbirth, and almost all babies born alive with anencephaly die within hours to a few days of birth.

There is no surgery, medicine or therapy that can change this outcome, because the essential parts of the brain have not formed. We know this is devastating to read, and we are so sorry if this is your situation.

What this means in practice is that care shifts from treating the baby to supporting you: helping you understand the diagnosis, giving you time and space, and supporting whatever decisions you make about the pregnancy and the birth. Your medical team and a counsellor can walk through your options with you compassionately.

What Are the Symptoms and How Is Anencephaly Diagnosed?

Anencephaly does not cause specific symptoms that a mother feels. It is found through prenatal testing (CDC):

• A blood or serum screening test may be abnormal, often showing a raised level of a substance called alpha-fetoprotein (AFP).

• An ultrasound scan can show anencephaly, often at the routine anomaly scan and sometimes earlier. Excess amniotic fluid (polyhydramnios) is sometimes seen alongside it.

• Occasionally it is diagnosed at birth, when it is immediately visible.

Because it can be picked up on scans, some families learn of it during pregnancy, which allows time, however painful, to prepare, ask questions, and make decisions with support. Read about prenatal scans and visits.

What Causes Anencephaly, and Was It Something I Did?

First, and most importantly: anencephaly is not caused by anything you did. It is not caused by stress, by working, by exercise, by a fall, by sex, by something you ate, or by an argument. Please do not carry that blame.

The exact cause is not fully understood. It is thought to result from a combination of genetic factors and other factors together. Researchers have identified some things that can increase the chance (CDC):

• Low folate (vitamin B9) levels in early pregnancy

• Pre-existing health conditions that are not well controlled, such as diabetes

• Certain medicines, such as some anti-seizure (epilepsy) medications

• Overheating or a high fever in early pregnancy

Having one of these does not mean you caused it, and many mothers have none of them. These are statistical risk factors across large populations, not a verdict on any individual pregnancy.

How Common Is Anencephaly?

Anencephaly is rare. In the United States, it is estimated to affect about 1 in every 4,762 babies (CDC). Neural tube defects, including anencephaly, are reported to be more common in India and South Asia than in many Western countries, which is part of why folic acid before and during early pregnancy is such an important public health message here. (Editorial note: if Mylo wishes to cite a specific Indian NTD incidence figure, please verify it against ICMR or a peer-reviewed Indian study before publishing; rates vary by region and study.)

Can Anencephaly Be Prevented?

For future pregnancies, and for other readers planning a pregnancy, there is one genuinely powerful step: folic acid, started before conception.

• Take 400 micrograms (mcg) of folic acid every day, ideally from three months before trying to conceive and through the first 12 weeks of pregnancy. This significantly reduces the chance of neural tube defects (CDC). Read Mylo's guide on folic acid for pregnancy.

• If you have had a previous pregnancy affected by a neural tube defect, or you have diabetes, a seizure disorder, or certain other conditions, you will be advised a much higher dose of 5 milligrams (mg) of folic acid, on prescription, for future pregnancies. This is important, because the chance of recurrence is higher, and the higher dose lowers it.

Because the neural tube closes so early, folic acid only works if it is already in your body at the time of conception. This is why it is started before pregnancy, not after a positive test. Other sensible steps include managing diabetes well before conceiving, reviewing any epilepsy or other medicines with your doctor before pregnancy, and avoiding overheating and untreated fevers in early pregnancy.

If You Have Received This Diagnosis: What Happens Next

There is no single right path, and your feelings are valid whatever they are. Your medical team will support you through the decisions ahead, which may include:

• Understanding your options for the pregnancy, which can include continuing the pregnancy with supportive (palliative) care planned for after birth, or ending the pregnancy. This is a deeply personal decision, and you are entitled to unhurried, non-judgemental counselling to make it.

• Planning the birth with your team so your wishes are respected.

• Emotional and grief support, including counselling, and time to hold and be with your baby if you wish.

• Talking about the future. When you are ready, your doctor can discuss what a future pregnancy would involve, including high-dose folic acid and closer monitoring.

Please ask your hospital what counselling and bereavement support they can connect you with. You deserve care and gentleness, not just information.

Anencephaly: Frequently Asked Questions

"Did stress or something I did cause my baby's anencephaly?"
No. Anencephaly is not caused by stress, emotions, work, exercise, a fall, or anything you ate or did. It happens because of how the neural tube formed in the earliest weeks, often before you knew you were pregnant. Please do not blame yourself.

"Can a baby with anencephaly survive?"
Sadly, no. Anencephaly is fatal and has no cure or treatment. Many pregnancies end in miscarriage or stillbirth, and babies born alive usually live only hours to a few days. We are very sorry.

"Will it happen again in my next pregnancy?"
The chance of it happening again is higher than average, but it is still not likely, and there is a lot that can be done to lower the risk. The most important step is high-dose folic acid (5 mg), started before you conceive, on your doctor's advice, along with closer monitoring. Talk to your doctor before trying again.

"Is anencephaly genetic or inherited?"
It is thought to come from a combination of genetic factors and other factors, rather than a single inherited gene in most cases. Having had one affected pregnancy raises the chance of recurrence, which is why extra folic acid and monitoring are advised next time. A specialist can discuss your specific situation.

"Can folic acid really prevent it?"
Folic acid before and during early pregnancy significantly lowers the risk of neural tube defects across populations. It cannot guarantee prevention in every case, but it is the single most effective step known, which is why it is recommended for everyone planning a pregnancy.

"How early can anencephaly be seen on a scan?"
It can often be seen on ultrasound, including at the routine anomaly scan and sometimes earlier, and screening blood tests may also flag it. Your doctor will explain what your specific scans showed.

When To Speak To Your Doctor

• If a scan or screening test has raised a concern, ask for a clear explanation and, if needed, referral to a fetal medicine specialist.

• If you are planning a pregnancy, especially after a previous neural tube defect, or if you have diabetes or take epilepsy medicines, speak to your doctor before conceiving about the right folic acid dose.

• If you are grieving a loss, please reach out to your doctor or a counsellor for support. This is not something you have to carry alone.

This article is for information and support only. It does not replace the care of your obstetrician, fetal medicine specialist or counsellor, who can guide you through your specific situation with compassion.

Bottom Line

Anencephaly is a rare and serious neural tube defect in which the brain and skull do not fully form, and it is sadly fatal with no cure. It develops in the earliest weeks of pregnancy and is not caused by anything the mother did, so if this is your experience, please do not blame yourself. For those planning a pregnancy, the most powerful protective step is folic acid started before conception, and a higher prescribed dose for anyone who has had a previously affected pregnancy. If you are facing this diagnosis, your medical team and a counsellor are there to support you, and you deserve that support fully.

References

All links verified live on 16 September 2026.

1. Anencephaly — Centers for Disease Control and Prevention (CDC), USA (updated January 2026). Source for the definition, fatal outcome and lack of treatment, prevalence (about 1 in 4,762 in the US), risk factors, diagnosis, and folic acid prevention (400 mcg).

2. Pregnancy vitamins and supplements — NHS, UK. Source for the higher-dose folic acid (5 mg) recommendation for higher-risk pregnancies, including a previous neural tube defect.

3. Folic acid for pregnancy — internal, for the detailed folic acid guidance.