Anencephaly

Anencephaly is when the neural tube that forms the brain and spinal cord doesn’t fully close at the top while the fetus is growing. It happens during the first 24 days of a pregnancy and is known as a neural tube defect (NTD). The most common types of NTDs are spina bifida and anencephaly.

With anencephaly, the brain doesn’t fully develop – there will be no forebrain (front part) and no cerebrum (the coordinating and thinking part). Often the rest of the brain isn’t covered over with skull and skin. Without a fully formed brain, the baby dies before or shortly after birth – within hours or days.  

In Aotearoa New Zealand, 5 to 6 babies in every 10,000 pregnancies are born with anencephaly, although many more are diagnosed with this condition during pregnancy. The number of pregnancies affected by NTDs is decreasing because there is more awareness of the importance of folic acid for babies’ development (see below).  

The image below shows how the front and top of the baby’s brain hasn’t developed and the top of the head has no bone or skin covering. 

Image credit: Centers for Disease Control and Prevention, National Center on Birth Defects and Developments; Disabilities, Wikimedia Commons

The cause is not clear but it’s likely be due to a combination of genes and environmental factors, eg, diet and medicines. While it’s not possible to prevent all cases of anencephaly, it is possible to decrease the risk of having a baby with this condition. 

Studies have shown that taking folic acid supplements for at least 1 month before getting pregnant and for the first 3 months of pregnancy can reduce the risk of having a baby with anencephaly and spina bifida.  Read more about folic acid in pregnancy.(external link) 

If you have a family history of any NTD, your risk is higher and the dose of folic acid you take also needs to be higher to be effective (see below).  

Use of anti-epileptic drugs also increases the risk of anencephaly, so if you're taking these medicines see your healthcare provider or specialist before you plan to become pregnant. 

Anencephaly can often be diagnosed during the optional screening tests you will be offered as part of your antenatal care. Screening tests can provide you with information about your baby’s growth and development. They can also tell you whether you or your baby are more likely to have a medical condition. Read more about antenatal screening tests. 

Screening tests used to diagnose anencephaly include:

Ultrasound scan: In most cases, signs of anencephaly are observed at the 11 to 14-week scan and, if not, will almost always be picked up at the 20-week scan.

Blood test:  If you have the second trimester maternal serum screening (a blood test taken between 14 and 20 weeks), one of the components measures how much alpha-fetoprotein (AFP) is in your blood. High levels of AFP may suggest the developing baby has a neural tube defect (eg, spina bifida or anencephaly) or some other developmental problem.

Diagnostic tests

If any of the screening tests suggest there's a higher risk of a genetic condition or anencephaly, further diagnostic testing will be arranged through your local Fetal Medicine team. Diagnostic tests include amniocentesis or chorionic villus sampling (CVS). If anencephaly is confirmed, what this means for you and your whānau will be explained as carefully as possible. You will be given time to decide what to do next. You may choose to continue with or terminate your pregnancy.

If you choose not to have an ultrasound scan during pregnancy, anencephaly might not be diagnosed until after the baby is born. 

Anencephaly is clearly seen at birth. Most babies with anencephaly are stillborn.  

Sadly, there is no treatment. Because their brain hasn’t fully developed and lacks important parts, the baby dies before or shortly after birth. There’s no chance of survival.

Talking with a trained counsellor can often be helpful in times like this. You and your whānau will usually be offered counselling through your local Fetal Medicine Unit. You can also find out more at Maternal Fetal Medicine Network(external link). The Network is a national organisation with hubs in Auckland, Wellington and Christchurch.  

Other support options include:  

• Sands:(external link) A network of parent-run, non-profit groups supporting families who have experienced the loss of a baby. 
• Grief counselling 
• Check with your general practice – some have access to free counselling through health improvement practitioners (HIPs). Read more about HIPs.  

Research shows that women who have a high level of folic acid before they become pregnant, are less likely to have a baby with neural tube defects. For it to work, supplementation should begin before you try to get pregnant, but if you didn’t start folic acid before you were pregnant it's still worth starting it as soon as you find out you're pregnant.

Wanting to get pregnant?

Ask your GP or nurse for a free folic acid prescription. You can also get this from your local pharmacy. Health New Zealand | Te Whatu Ora recommends you take these folic-acid only tablets for at least 4 weeks prior to conception and for 12 weeks after conception to reduce the risk of NTDs.  

The recommended dose of folic acid for most women is 0.8 mg per day. Women who are at higher risk of having a baby with a neural defect (eg, those who are taking certain medicines or who have had a previous child with a neural tube defect) should take 5 mg of folic acid a day for at least a month before getting pregnant. 

Read more about folic acid in pregnancy.

Watch 'The Short Life of Poe Elijah Williams a baby born with Anencephaly into Much Love' by Ozventures(external link)
Note: You may find this video upsetting.

Future pregnancies are not usually affected. However, there is a very small increased risk of having another baby with anencephaly. Your best chance of preventing it is to take the recommended amount of folic acid.