What is one of the main reasons for physiologic jaundice in newborns?

Physiologic jaundice in newborns primarily occurs due to high hemoglobin turnover. After birth, a newborn undergoes a rapid breakdown of fetal hemoglobin as their body transitions to producing adult hemoglobin. This breakdown results in the release of bilirubin, which the immature liver may not adequately process at first.

In newborns, especially those born prematurely, the liver enzymes responsible for conjugating bilirubin are not yet fully developed, leading to an accumulation of unconjugated bilirubin in the blood. This condition typically manifests during the first week of life and is considered physiologic because it generally resolves as the liver matures and becomes more efficient at processing bilirubin.

Other factors, such as immature kidney function and improper feeding, can contribute to jaundice but are not the primary reasons for physiologic jaundice. Exposure to sunlight promotes the breakdown of bilirubin and is often used as a treatment method rather than a cause. Therefore, high hemoglobin turnover is recognized as the main reason for physiological jaundice in this context.