**Core Concept**
Delayed cord clamping in preterm infants is a crucial practice to prevent anemia of prematurity and promote better hemodynamic stability. This practice involves waiting for at least 30-60 seconds after birth before clamping the umbilical cord, allowing the baby to receive a significant amount of placental blood.

**Why the Correct Answer is Right**
Delaying cord clamping allows the preterm infant to receive up to 50-100 mL of blood from the placenta, which increases their blood volume and improves their hemoglobin levels. This is especially important in preterm infants, who are at a higher risk of anemia due to their limited red blood cell mass and increased blood loss during delivery. By delaying cord clamping, healthcare providers can help reduce the incidence of anemia of prematurity and promote better cardiovascular stability in these vulnerable infants.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because there is no evidence to support a delay of less than 30 seconds in preterm infants. In fact, the American Academy of Pediatrics recommends delaying cord clamping for at least 30-60 seconds after birth.

**Option B:** This option is incorrect because delayed cord clamping is beneficial for preterm infants, not just those born at term. Preterm infants are at a higher risk of anemia and cardiovascular instability, making delayed cord clamping a crucial practice in their care.

**Option C:** This option is incorrect because the exact timing of delayed cord clamping is not strictly defined, but it is generally accepted to be at least 30-60 seconds after birth. The American Heart Association recommends delaying cord clamping for at least 30-60 seconds, but this can vary depending on individual circumstances.

**Clinical Pearl / High-Yield Fact**
Remember that delayed cord clamping is a simple yet effective practice that can significantly improve the outcomes of preterm infants. This practice should be implemented in all preterm births, regardless of the infant's weight or gestational age.

**Correct Answer: D. 30-60 seconds.**