Blood volume in a preterm infant is approximately:

• A. 65 to 70 mls/kg
• B. 80 to 85 mls/kg
• C. 100 to 120 mls/kg
• D. 140 to 160 mls/kg

Answer: (C)

In preterm infants, the amount of blood present per kilogram of body weight is higher than in term babies. A typical estimate for a preterm newborn is about 100 to 120 mL per kilogram. This comes from the fact that preterm infants have a larger proportion of body water and extracellular fluid, and their circulatory system is still maturing, so maintaining adequate perfusion requires a relatively larger circulating volume per unit body weight. Clinically, this higher per‑kg blood volume helps guide fluid management and transfusion decisions in these infants. Values well below this range would underestimate circulating volume and risk under-resuscitation, while substantially higher ranges are not consistent with neonatal physiology.