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Neural tube defects-Why is folic acid important during pregnancy?

Neural tube defects

Neural tube defects are congenital defects of the brain, spinal cord, and spinal cord. They occur in the first month of pregnancy, many times before the woman knows she is pregnant.

In this article, we will explain the important role of folic acid in Neural tube defects as well as in pregnancy.

Folic acid or folate (vitamin B9) is an essential nutrient for our health as it is necessary for the formation of DNA and a series of enzymatic reactions involved in the production of amino acids and in the metabolism of vitamins.

During pregnancy, the body’s demand for folate increases considerably, since this vitamin is also necessary for the growth and development of the fetus. Folic acid deficiency during pregnancy is associated with severe fetal abnormalities, especially so-called neural tube defects. Anomalies in neural tube formation are the second most common cause of fetal malformation, losing only to congenital heart disease.

The neural tube is an embryonic structure that gives rise to the spinal cord, vertebrae, meningeal, brain and skull. Defects in the formation of the nervous system of the fetus occur in pregnant women who have had unsatisfactory levels of folic acid in the body during pregnancy.

The terms folic acid and folate are often used synonymously, but they are not exactly the same. Folic acid is the synthetic form of folate, also called vitamin B9. In this article, however, we will use only folic acid, both for the natural and synthetic forms, as this is a term best known by the lay population.


The defect in neural tube formation can lead to several fetal malformations, such as:

Anencephaly, which is the absence of a part of the brain and the top of the skull.

Spina bifida, a malformation of the spinal cord, in which some vertebrae are not completely formed, allowing part of the spinal cord to project into the opening in the bones.

Encephalocele, which is a defect in which the herniation of the brain and meninges occurs through openings in the skull.

The structural problems generated by defects in the neural tube are usually severe and without definitive treatment. When they do not lead to the death of the baby, they usually cause significant disability.

One of the major causes of neural tube malformations is folic acid deficiency during pregnancy. It is therefore not surprising that this type of malformation can be prevented with folic acid supplementation. Also, Read During pregnancy what to eat and what not to eat

However, there is a big problem that makes the solution not as simple as it seems. The neural tube forms in the first 4 weeks of embryo life. As most women find that they are pregnant after at least 5 or 6 weeks of gestation, the process of neural tube formation is already completed at the time of pregnancy diagnosis. After 6 weeks of gestation, the folic acid preventive action is much lower.

Therefore, every woman who intends to become pregnant should start taking folic acid for at least 1 month before becoming pregnant, in order to ensure satisfactory levels when it comes to the formation of the fetal nervous system.


Folic acid is a vitamin of the family of vitamin B, necessary for the synthesis of DNA and new cells. During pregnancy, the woman needs sufficient amounts of folic acid for her and the fetus, which is in the process of formation.

Folic acid is found naturally in foods such as spinach, lettuce, broccoli, beans, cereals, brussels sprouts, potatoes, rice, fruits and liver meat.

Currently, in many countries around the world, various foods are supplemented with folic acid, including various cereals such as rice, wheat, and corn. In Brazil, wheat flour and maize must be enriched with folic acid by law. In the United States, the FDA (Food and Drug Administration) since 1998 indicates folic acid supplementation in all cereals. This attitude reduces the incidence of neural tube defects in that country by 50%.

Folic acid is important in preventing neural tube defects, but it is also essential to fetal growth, so it should be consumed before and during pregnancy.


Although a naturally occurring vitamin in various foods, folic acid replacement is the most effective way to prevent neural tube defects. This occurs because the bioavailability of folic acid in supplements or artificially enriched foods is substantially greater than the bioavailability of folate obtained from natural foods.

A US study conducted between 2007 and 2012 showed that 1 in 4 Americans showed folic acid levels below recommended levels. There are many factors that can explain this high number, among them:

Low carbohydrate diets can lead to folic acid deficiency since the doughs are bread made with fortified grains.

Some medicines, such as carbamazepine, valproic acid, phenytoin, phenobarbital, metformin, methotrexate, sulfasalazine, triamterene, and sulfamethoxazole-trimethoprim, interfere with folic acid levels.

High consumption of foods designated as “organic”, which do not receive an artificial supplement of folic acid.

Medical or surgical conditions that cause intestinal malabsorption, such as celiac disease, Crohn’s disease, or bowel resection.

Folic acid replacement before and during pregnancy helps to reduce the relevant risk of neural tube defects, however, it does not eliminate the risk by 100%. Situations such as poorly controlled diabetes, chromosomal defects, and obesity are also associated with an increased risk of neural tube problems. You can also read about Hypertension in pregnancy

It is estimated that acid replacement is able to prevent approximately 50 to 70% of cases of neural tube defects.

Related: Preparing for childbirth: All you need to know


In some women, diet alone may not be enough to maintain good levels of folic acid during pregnancy.

Related: Weight in pregnancy- average weight gain during pregnancy

Therefore, for safety, the supplement is recommended for all pregnant women and women wishing to become pregnant. In fact, up to half of all pregnancies occur without planning, the safest is that all women of childbearing age are concerned about folic acid use.

Neural tube defects
Why is folic acid important during pregnancy?

The minimum daily dose of folic acid recommended for pregnant women is 0.4 mg per day. Tablets from 0.2 mg to 15 mg are available on the market. The most common form is the 5 mg folic acid tablet, which is more than enough to replenish the mother’s reserves.

In pregnant women at high risk for folic acid deficiency, such as women who use one of the aforementioned drugs, the minimum dose of folic acid that is 5 mg per day is recommended.

Also Read: During pregnancy what to eat and what not to eat

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