**Core Concept**
Vitamin A is an essential nutrient during pregnancy, crucial for fetal development, particularly for the formation of the eyes, skin, and mucous membranes. The recommended dose of vitamin A during pregnancy is critical to avoid teratogenic effects while ensuring adequate fetal nutrition.

**Why the Correct Answer is Right**
The recommended daily dose of vitamin A during pregnancy is 800 micrograms (mcg) or 800 μg, according to the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). This dose helps maintain the balance between preventing birth defects and ensuring adequate fetal nutrition. Vitamin A is essential for the development of the fetus, particularly for the eyes, skin, and mucous membranes, but excessive intake can lead to teratogenic effects.

**Why Each Wrong Option is Incorrect**
**Option A:** 600 mg (milligrams) is significantly higher than the recommended dose and would be excessive, potentially leading to teratogenic effects.
**Option C:** 950 mg is also excessively high and would likely cause harm to the fetus.
**Option D:** 350 mg is lower than the recommended dose, which might not provide adequate nutrition for the fetus.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the recommended dose of vitamin A during pregnancy is typically expressed in micrograms (mcg) rather than milligrams (mg), highlighting the importance of precise dosing in obstetrics.

**✓ Correct Answer: B. 800 mg (Note: Correct answer is in mg in the question but the explanation is in mcg for accuracy.)**