**Core Concept**
Intrauterine Growth Restriction (IUGR) refers to a condition where a fetus does not grow at a normal rate inside the womb. IUGR can be categorized into two types: symmetrical and asymmetrical. Symmetrical IUGR affects all fetal body parts proportionally, whereas asymmetrical IUGR affects certain body parts disproportionately.

**Why the Correct Answer is Right**
The correct answer states that all of the above options are true regarding IUGR. Asymmetrical IUGR is indeed more common than symmetrical IUGR. In asymmetrical IUGR, the head and brain are relatively spared, whereas in symmetrical IUGR, all body parts are affected proportionally. A normal ponderal index in symmetrical IUGR is a hallmark of this condition, as the weight and length of the fetus are equally reduced. Asymmetrical IUGR has a better prognosis than symmetrical IUGR because the brain is relatively spared, and the fetus has a better chance of survival and normal development.

**Why Each Wrong Option is Incorrect**
**Option A:** Asymmetrical IUGR is actually less common than symmetrical IUGR. This is because symmetrical IUGR is often associated with chromosomal abnormalities or maternal medical conditions.

**Option B:** In symmetrical IUGR, the ponderal index is often reduced, not normal. The ponderal index is a measure of fetal growth that takes into account the weight and length of the fetus. In symmetrical IUGR, the weight and length of the fetus are equally reduced, resulting in a decreased ponderal index.

**Option C:** While asymmetrical IUGR has a better prognosis than symmetrical IUGR, this is not always the case. Asymmetrical IUGR can still be associated with significant morbidity and mortality, particularly if the underlying cause is not identified and treated.

**Clinical Pearl / High-Yield Fact**
A key feature of asymmetrical IUGR is the presence of a "thin" or "long" fetus, which can be detected on ultrasound. This is because the head and brain are relatively spared, resulting in a disproportionately large head in relation to the body. A "thin" or "long" fetus is a red flag for asymmetrical IUGR and warrants further evaluation.

**✓ Correct Answer: D. All of the above**