Neural Tube Defects
Foods containing high levels of folate, such an assortment of fruits and vegetables, are an important part of a healthy diet. Researchers report new details on the link between low folate intake and an increased risk for colon cancer. (Credit: USDA Agricultural Research Service)
Please note that this section contains my personal notes from my readings on this topic.
From Whats Going on in There? : How the Brain and Mind Develop in the First Five Years of Life
Neural Tube Defects (NTDs)
- One of the most sensitive periods in brain development is during its earliest formation. Between twenty-two and twenty-eight days after conception, the neural tube must fuse along its entire length to create a properly enclosed central nervous system… Failure of the tube to close properly can result in a number of neural tube defects (NTDs).
- NTDs have several suspected causes and have been linked to genetic, ethnic, nutritional, drug, and environmental factors. It is probably the combination of several of these that produces an abnormality in any particular fetus. A genetic predisposition is suggested…
- NTDs are more common when mothers suffer from particular illnesses during pregnancy. Women with insulin-dependent diabetes have a considerably higher risk, although the better their diabetes is controlled, the lower is their risk for both NTDs and other types of fetal abnormalities. Various medications may also play a role (detailed in the book).
- Of wider concern is the possibility that a mother’s elevated body temperature increases the risk of NTDs. Although not all studies agree, the majority indicate that mothers who either experienced an illness-related fever or who used a hot tub or sauna during early pregnancy were about twice as likely to have a fetus with an NTD than mothers who did not have a temperature-elevating experience in the first trimester. Temperature elevation of more than 1.5 degrees Celsius (or 2.7 degrees Fahrenheit) is known to perturb early development in both animals and humans; presumably, if this disruption occurs while the neural tube is trying to close, an NTD is more likely.
- First published in 1981 and widely confirmed by 1992, it was found that women who take the B-complex vitamin folic acid at the time of conception and during the first several weeks of pregnancy are substantially less likely to have a fetus with a neural tube defect than women who do not take folic acid. The initial studies were conducted on women who had already had a pregnancy with a NTD, because their risk of a subsequent NTD is so much higher than for women without such a history. This simple measure — taking a multivitamin pill that includes folic acid — reduced their chance of having a second NTD by an impressive 76%. After this finding, studies were extended to a general population of women, and folic acid was found to prevent about 60% of first-time NTD occurrences. This result has been replicated in many different countries.
- A greater problem with ensuring adequate folate intake is that about half of all pregnancies (in the United States and Canada) are not planned. Because neural tube closure begins so early — just eight days after a missed period — many women simply will not get around to taking folic acid at the time it is actually needed. This very early timing is the reason why health agencies in many countries have begun mandating the addition of folic acid to widely consumed foods. In the United States, folic acid fortification has been required since the beginning of 1998 for all enriched grains — flour, cornmeal, bread, pasta, rice, and cereal — in amounts estimated to raise the average woman’s consumption by 0.1 milligram per day. While this fortification should reduce the prevalence of NTDs in the population at large, it is modest enough that women are still advised to take a supplement beginning at least one month before conception and continuing through the first trimester of pregnancy.
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The information contained throughout this blog / website should not be used as a substitute for the medical care and advice of your pediatrician / physician.