Why are bilirubin levels usually higher in the first 24 hours after birth?

Bilirubin levels tend to be higher in newborns within the first 24 hours after birth primarily due to the physiological changes that occur as the newborn adapts to life outside the womb. After delivery, the infant's liver is still maturing and may not initially process bilirubin effectively.

During the birthing process, it is common for babies to experience some degree of bruising or trauma, especially if there were complications like a prolonged labor or the use of forceps. This trauma can result in an increased breakdown of red blood cells, leading to a higher production of bilirubin. Bilirubin is a byproduct of hemolysis, and with the body breaking down more red blood cells than the immature liver can handle, levels tend to spike in this early postnatal period.

The situation emphasizes the importance of carefully monitoring bilirubin levels in newborns, as excessively high levels can lead to conditions like jaundice. While other factors such as feeding practices and medications may influence bilirubin levels later on, the primary reason for the elevated levels in the first day post-delivery relates to the natural process of delivery and the associated physical traumas.