Which nutrient supplementation reduces neural tube defect risk when given periconceptionally?

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

Answer: (C)

The key idea is that neural tube formation happens very early in pregnancy, often before many women know they’re pregnant. Adequate folate (folic acid) around conception supports neural tube closure by providing essential parts for DNA synthesis and cell division in the rapidly developing embryo. Because of this timing, taking folic acid periconceptionally (before conception and in early pregnancy) markedly lowers the risk of neural tube defects. The typical preventive dose is about 400 micrograms daily for most women, with higher doses (such as 4 mg daily) advised for those at higher risk (e.g., prior neural tube defect pregnancy or certain anticonvulsant therapies). The other nutrients listed don’t have a proven impact on neural tube defect risk. Iron prevents maternal anemia, vitamin C supports general health and iron absorption, and vitamin D is important for bone health, but none are linked to reducing neural tube defect risk in the periconceptional window.