Folic acid required in first trimester of pregnancy in a woman with a history of NTD is:
**Core Concept**
Folic acid supplementation in pregnancy is crucial for preventing neural tube defects (NTDs) in the developing fetus. The neural tube forms within the first month of pregnancy, and folic acid plays a critical role in its closure.
**Why the Correct Answer is Right**
The recommended dose of folic acid for women with a history of NTDs is significantly higher than for the general population. This is because these women are at an increased risk of having a child with an NTD. A dose of 4-5 mg of folic acid per day is recommended for women with a history of NTDs, starting at least one month before conception and continuing through the first trimester of pregnancy. This high dose is necessary to ensure that the fetus has an adequate supply of folic acid to prevent NTDs.
**Why Each Wrong Option is Incorrect**
**Option A:** 0.4 mg is the recommended daily dose for the general population to prevent NTDs, but it is not sufficient for women with a history of NTDs.
**Option B:** 1 mg is still below the recommended dose for women with a history of NTDs and would not provide adequate protection against NTDs.
**Option C:** 10 mg is excessive and not recommended for routine supplementation in pregnancy.
**Clinical Pearl / High-Yield Fact**
Women with a history of NTDs should take folic acid supplementation for at least three months before conception and continue through the first trimester to prevent recurrence.
**Correct Answer: C. 4-5 mg**