**Core Concept**
Caudal regression syndrome is a rare congenital disorder characterized by the abnormal development of the lower spine, often associated with other organ system anomalies. It is a type of caudal dysplasia, which affects the caudal region of the embryo, leading to various degrees of spinal cord and vertebral anomalies.

**Why the Correct Answer is Right**
Caudal regression syndrome is strongly associated with maternal diabetes mellitus, particularly gestational diabetes. The exact pathophysiology is not fully understood, but it is thought to be related to the abnormal fetal environment and possible teratogenic effects of maternal hyperglycemia. The increased glucose levels in the maternal bloodstream may lead to the overproduction of insulin, which crosses the placenta and affects the fetus, causing developmental abnormalities.

**Why Each Wrong Option is Incorrect**
**Option A:** While maternal hypertension is a significant risk factor for various fetal anomalies, it is not specifically associated with caudal regression syndrome.
**Option B:** Maternal obesity is a risk factor for gestational diabetes, which is linked to caudal regression syndrome, but it is not a direct cause.
**Option C:** Maternal age is a risk factor for various fetal anomalies, but it is not specifically associated with caudal regression syndrome.

**Clinical Pearl / High-Yield Fact**
Caudal regression syndrome is often associated with other organ system anomalies, such as renal agenesis, omphalocele, and cardiac defects. A high index of suspicion should be maintained in infants born to diabetic mothers with lower spine anomalies.

**Correct Answer:** D.