Dietary supplement alone can not compensate for the increased requirement of which nutrient in pregnant women :
**Core Concept**
During pregnancy, the maternal body undergoes various physiological changes to support the growth and development of the fetus. One crucial adaptation involves the increased demand for certain nutrients, which are essential for fetal development and maternal health. This heightened requirement is a result of the growing fetus's needs and the increased metabolic rate of the mother.
**Why the Correct Answer is Right**
The correct answer is **Folic acid**. Folic acid is a B-complex vitamin that plays a vital role in fetal development, particularly in preventing neural tube defects (NTDs) such as spina bifida and anencephaly. The demand for folic acid increases significantly during pregnancy, and dietary supplements alone may not be sufficient to meet this increased requirement. The recommended daily intake of folic acid for pregnant women is 600-800 mcg, which can be challenging to achieve through dietary sources alone.
**Why Each Wrong Option is Incorrect**
* **Option A:** Iron - While iron supplementation is essential for pregnant women, the increased requirement for iron is generally met through dietary sources, such as red meat, poultry, and fortified cereals.
* **Option B:** Calcium - Calcium supplementation is also crucial for pregnant women, particularly to support fetal bone development. However, dietary sources such as dairy products, leafy greens, and fortified plant-based milk can provide sufficient calcium.
* **Option C:** Vitamin D - Vitamin D is essential for bone health, but the increased requirement during pregnancy can be met through a combination of sunlight exposure, dietary sources, and supplements.
**Clinical Pearl / High-Yield Fact**
Pregnant women should consume folic acid-rich foods, such as dark leafy greens, citrus fruits, and fortified cereals, in addition to taking a prenatal vitamin supplement to meet their increased folic acid requirements.
**Correct Answer:** D.