A rare congenital malformation of the nervous system, anencephaly results in the absence of a large brain and most often leads to fetal death in utero.

Like spina bifida, anencephaly is linked to a failure to close the neural tube. In the case of spina bifida, it is the spinal cord that is affected by this developmental disorder of the nervous system that occurs between the 5th and the 6th week of pregnancy. In the case of anencephaly, it is the brain. Much of the brain, skull and scalp are missing.

The prevalence of anencephaly at birth is between 1 case in 5000 and 1 case in 2000, with a higher rate in the British Isles, China, Mexico and Turkey.

Anencephaly is thought to be linked both to genetic factors and to environmental factors. Specialists mention in particular a deficit in folic acid and zinc in the mother. Maternal obesity has also been identified as a risk factor. Even in the absence of gestational diabetes, the risk of anencephaly is 2-3 times higher in maternal obesity. Gestational diabetes further amplifies this risk.

Anencephaly is generally diagnosed during the second follow-up ultrasound, called a “morpho echo”, during the 5th month of pregnancy.

Most children with anencephaly are still born. In very rare cases, babies survive for a few hours or even a few days.

The fatal outcome of this major neurological abnormality makes it an indication for medical termination of pregnancy.

To prevent neural tube closure abnormalities, expectant mothers are recommended to take 400 micrograms of folic acid (also called “folate” or “vitamin B9”) per day. This supplementation reduces the risk of failure of the neural tube to close in almost two-thirds of cases.

If you want to become pregnant, take vitamin B9 as soon as you stop contraception and continue during the first two months of pregnancy. Prescribed by a doctor, it is reimbursed by the Health Insurance. At the same time, it is advisable to eat a diet rich in folate. It is found in large quantities in chickpeas, green vegetables (spinach, watercress, chicory, dandelion, lamb’s lettuce), in nuts and chestnuts.