Why are premature infants slightly acidotic?

Premature infants are slightly acidotic primarily due to their immature renal function, which affects their ability to concentrate urine effectively. The kidneys of these infants are not fully developed, leading to an impaired ability to excrete hydrogen ions and retain bicarbonate adequately. As a result, this impaired renal function can contribute to a mild acidotic state due to the accumulation of acids and inability to maintain normal acid-base balance.

The other choices do not accurately address the primary reason for the slight acidosis in premature infants. For instance, excess bicarbonate production is not characteristic of the condition; in fact, these infants typically struggle to maintain adequate bicarbonate levels. Increased metabolic rate does occur as a compensatory mechanism in response to various stresses, but it is not the core reason for their acidotic state. Additionally, while premature infants may have higher levels of carbon dioxide due to respiratory immaturity, this alone isn't the sole factor leading to acidosis without considering their renal function.