Which intervention has been shown to reduce the risk of neural tube defects when begun before conception?

• A. Iron
• B. Calcium
• C. Vitamin B12
• D. Folic acid

Answer: (D)

Preventing neural tube defects relies on adequate folate during the very early days of pregnancy. The neural tube forms and closes within the first month of gestation, often before a woman realizes she’s pregnant. Folate is essential for DNA synthesis and rapid cell division needed for proper neural tube development, so starting folic acid before conception ensures the body has enough folate during that critical window, markedly reducing the risk of defects like spina bifida and anencephaly.

Iron and calcium address different needs (blood production and bone health) and don’t have the same proven effect on neural tube defect risk when begun preconception. Vitamin B12 is important for folate metabolism, but the decisive preventive effect in this context comes from folic acid itself, not B12 alone. Current guidelines call for about 400 micrograms of folic acid daily for women planning pregnancy, with higher doses (around 4 milligrams daily) for those with a prior neural tube defect-affected pregnancy, starting before conception and continuing through the early first trimester.