Neural tube defects (fetus)

Neural tube defects are birth defects of the brain, spine or spinal cord. They start in the first month of pregnancy, often before a woman knows she is pregnant. The two most common are spina bifida and anencephaly. Getting enough folic acid before and during pregnancy prevents most of them. There is no cure; the damage that is present at birth is usually permanent, although treatments can sometimes prevent further damage and help with complications. They are usually found before the baby is born, through lab or imaging tests.

Condition
In this atlas

Overview

Technical summary

This is a condition of the fetus, so the atlas files it under the fetal development care area. The MedlinePlus health topic page (last updated September 16, 2025) supplies the plain description. A 2023 evidence update for a US screening statement (JAMA) opens by calling neural tube defects among the most common birth defects in the United States. Evidence that folic acid prevents them is on the folic acid supplementation page; the MRC Vitamin Study result there applies to women who had a previous affected pregnancy.

Recognition

Neural tube defects are usually diagnosed before the infant is born, through lab or imaging tests.

Burden

No burden claims are published.

Claims and evidence

No claims are published for this condition yet.

Clinical links

Each link reports what one cited claim says about one population. "Evaluated for" means studied, not shown to work. These links do not show that anything is effective or right for you.

Claim, not a settled fact Evaluated for this: Folic acid supplementation before and in early pregnancy (Evaluated for, seen from the other side)
Applies to Fetal
- Fetuses and infants of women at high risk of a pregnancy with a neural tube defect because of a previous affected pregnancy. 1817 women were allocated at random; 1195 had a completed pregnancy in which the fetus or infant was known to have or not have a neural tube defect. The women took the supplement; the outcome is counted in the fetus or infant.
- 33 centres in seven countries; the abstract does not name the countries or describe the settings.
- Seven countries; the abstract does not name them.
- Supplementation around the time of conception; outcome at the end of the pregnancy
- Gestational age Not reported
- Postnatal age Not reported
Follow-up Until a completed pregnancy in which the fetus or infant was known to have or not have a neural tube defect
In the MRC Vitamin Study, a randomised double-blind trial with a factorial design at 33 centres in seven countries, women at high risk of a pregnancy with a neural tube defect (because of a previous affected pregnancy) were given folic acid, a mixture of seven other vitamins, both, or neither. Of 1195 completed pregnancies in which the fetus or infant was known to have or not have a neural tube defect, 27 had a neural tube defect: 6 in the folic acid groups and 21 in the two other groups. The authors report a 72% protective effect (relative risk 0.28, 95% confidence interval 0.12 to 0.71). The other vitamins showed no significant protective effect (relative risk 0.80, 95% CI 0.32 to 1.72). The abstract reports no demonstrable harm from folic acid, with limited ability to detect rare or slight adverse effects.
Limitations. Only the PubMed abstract was read. It does not give the folic acid dose, the numbers of women in each group, or the names of the countries. The counts pool the groups that received folic acid (alone or with other vitamins) against the groups that did not, so per-group denominators are not available and are not computed. The result is for women with a previous affected pregnancy; it does not by itself show the size of the benefit for women without one. 1817 women were allocated at random and 1195 are in the pregnancies the abstract counts.

Record details

Record id: maternal:neural-tube-defects
Content hash: 524ece2596225d88121d78b974e87435f775b5b4664fd70f5fef5a7f93aa9729