Neural tube defects or NTDs are serious congenital malformations of the brain and spinal cord that occur during the first weeks of pregnancy when the neural tube (embryonic structure from which the central nervous system of the fetus develops) does not close properly.
The most common NTDs are anencephaly (brain defect) and spina bifida (spinal cord defect).
While anencephaly always leads to the death of the baby before birth or within a few days, spina bifida has very different consequences, ranging from the absence of symptoms, in the mildest cases, to severe physical and mental disabilities, in the most severe forms.
Numerous studies have shown that a lack of folic acid in the early stages of pregnancy significantly increases the risk of such malformations in new-borns.
Folic acid is a water-soluble vitamin of group B, known as vitamin B9, essential for the formation of hemoglobin, for the synthesis of DNA and proteins and it is particularly important for tissues that undergo intense proliferation processes and differentiation, for example, embryonic tissues.
Therefore, during pregnancy the daily requirement of folic acid increases.
As recommended by the Italian Folic Acid Promotion Network for the Primary Prevention of Congenital Defects:
“A woman of childbearing age, who suspects or does not exclude a pregnancy, should take an additional amount of 0.4 mg/day, starting at least 1 month before conception to the third month of pregnancy (periconceptional period).”
Systematic reviews of scientific literature highlighted how a correct folic acid supplementation can reduce the risk of NTDs by up to 70%.
Bibliography: Folic acid and folates, Italian National Institute of Health.  Italian Network Folic Acid Promotion for the Primary Prevention of Congenital Defects, Italian National Institute of Health