Molloy, A. M. et al. Maternal vitamin B12 status and risk of neural tube defects in a population with high neural tube defect prevalence and no folic acid fortification. Pediatrics 123, 917–923 (2009). Show Low maternal vitamin B12 status is an independent risk factor for having a child with a neural-tube defect, according to a study published in Pediatrics. Adequate intake of folic acid can prevent the majority of neural-tube defects. Fortification of grain with folic acid in countries including the US has reduced the prevalence of these defects; however, further folic-acid fortification is unlikely, as concerns about possible adverse effects exist. To further reduce prevalence of neural-tube defects, additional, modifiable maternal risk factors for these defects must be identified. Molloy and colleagues focused on vitamin B12, because of its close metabolic association with folate and evidence of a link between low maternal levels of the vitamin and pregnancies affected by neural-tube defects. In three separate, nested, case–control studies, the investigators analyzed concentrations of vitamin B12 in blood samples taken from pregnant women at an average 15 weeks of gestation who had a child with neural-tube defects at either that pregnancy or a previous one. Crucially, the samples used (from the 1980s) predated widespread folic-acid fortification. In all three groups (after adjustment for folate) women with vitamin B12 concentrations in the lowest quartile had a twofold to threefold increased risk of having a child with a neural-tube defects compared with those in the highest quartile. The majority of risk was associated with vitamin B12 concentrations of <184 pmol/l. The researchers conclude that folate and vitamin B12 jointly influence a woman's risk of having a child with neural-tube defects and that women can reduce this risk by ensuring that they have adequate vitamin B12 levels before they become pregnant.
Neural tube defects (also called NTDs) are birth defects of the brain and spinal cord. Birth defects are health conditions that are present at birth. They change the shape or function of one or more parts of the body. Birth defects can cause problems in overall health, how the body develops or how the body works. A baby’s neural tube normally starts out as a tiny, flat ribbon that turns into a tube by the end of the first month of pregnancy. If the tube doesn’t close completely, an NTD can happen. NTDs can cause serious problems for babies, including death. NTDs happen in about 3,000 pregnancies each year in the United States. Hispanic women are more likely than non-Hispanic women to have a baby with an NTD. The two most common NTDs are spina bifida and anencephaly. Spina bifida affects about 1,500 babies a year in the United States. If your baby has spina bifida, the tiny bones of the spine don’t close completely, and part of the spinal cord pokes through the spine. Children with spina bifida may have paralyzed legs (not able to move) and problems controlling their bladder and bowel (going to the bathroom). Milder forms of spina bifida may cause fewer problems for children. Anencephaly is one of the most severe NTDs. It affects about 1,000 babies each year in the United States. Anencephaly is caused when the upper part of the neural tube that forms the brain doesn’t close completely. Babies with this condition are missing major parts of the brain, skull and scalp. They do not survive long after birth, usually for just a few hours. Girls are 3 times more likely than boys to have anencephaly. Taking folic acid before and during early pregnancy can help prevent NTDs in your baby. Folic acid is a B vitamin that every cell in your body needs for normal growth and development. What causes NTDs?We’re not exactly sure what causes NTDs. Experts think some may be caused by genetics. This means an NTD can be passed from parents to children through genes. Genes are part of your body’s cells that stores instructions for the way your body grows, looks and works. NTDs also may be caused by things in your environment, which includes where you live, where you work, the kinds of foods you eat or have access to and how you like to spend your time. Some things in your environment can be harmful to a pregnancy, like certain drugs, cigarette smoke, air pollution and lead. Are you at risk for having a baby with an NTD?Any woman can have a baby with an NTD. But there are things that may make you more likely than other women to have a baby with an NTD. These are called risk factors. Your risk for having a baby with an NTD is higher if:
Other risk factors for NTDs include:
How can you help prevent NTDs in your baby?Taking folic acid before and during early pregnancy can help prevent NTDs in your baby. NTDs happen in the first month of pregnancy, before you may know you’re pregnant. This is why it’s important to have enough folic acid in your body before you get pregnant. Most womenTo help prevent NTDs in your baby, take a vitamin supplement with 400 mcg of folic acid every day before getting pregnant. A supplement is a product you take to make up for certain nutrients that you don’t get enough of in the foods you eat. Start taking this amount of folic acid each day at least 1 month before pregnancy and through the first 12 weeks of pregnancy. Your folic acid supplement can be:
Take a vitamin supplement with 400 mcg of folic acid each day, even if you’re not trying to get pregnant. Women at high risk for NTDs If you’re at high risk for having a baby with an NTD, it’s recommended you take 4,000 mcg of folic acid each day to help prevent an NTD. Start taking 4,000 mcg 3 months before you get pregnant through 12 weeks of pregnancy. You’re at high risk if:
Studies show that taking 4,000 mcg of folic acid before and during early pregnancy can help reduce your risk of having another baby with an NTD by about 70 percent. Ask your provider how to safely get this much folic acid. It’s not safe to take several multivitamins or prenatal vitamins because you can get too much of other nutrients, which may be harmful to your health. Your provider can help you figure out the best and safest way for you to get the right amount of folic acid. Can you get folic acid from food?Yes! You can get folic acid from foods that are fortified with folic acid. Fortified means a food has folic acid added to it. Check the product label to see how much folic acid you get in each serving. Look for the word “fortified” or “enriched” on labels on foods like:
Some fruits and vegetables are good sources of folic acid. When folic acid is naturally in a food, it’s called folate. Foods that are good sources of folate are:
It’s hard to get all the folic acid you need from food. Even if you eat foods that have folic acid in them, take your vitamin supplement each day, too. Can you find out if your baby has an NTD before birth?Yes. You can get prenatal tests (medical tests you get during pregnancy) called screening tests to find out if your baby is at increased risk of having an NTD. Screening tests for NTDs include:
If a screening test shows an increased risk of NTDs, your provider may recommend a diagnostic test to find out for sure if your baby has an NTD. Diagnostic tests for NTDs include:
If you find out that your baby has an NTD, talk to your health care provider to learn more about your baby’s condition and options for birth and treatment. For example:
More informationLast reviewed: February, 2022 |