What cardiac change occurs in the newborn shortly after birth?

Cardiac output in the newborn does indeed double shortly after birth due to the increased demand for oxygen as they transition from intrauterine to extrauterine life. This increased demand is driven by the onset of breathing air, which requires higher levels of oxygen and leads to reduced pulmonary vascular resistance. Alongside the opening of the pulmonary circulation, these factors contribute to the adaptation of the newborn's circulatory system.

The transition period is critical as the newborn's body adjusts from relying on the placenta for oxygenation to utilizing its lungs. The heart must efficiently pump blood to various organs and tissues to meet this heightened need for oxygen, which entails a significant increase in cardiac output—essential for ensuring that vital organs receive adequate oxygenation and nutrients immediately after birth.

Other cardiac changes, such as the changes in flow patterns between the right and left ventricles or the status of the ductus arteriosus, also occur but are secondary to this critical increase in cardiac output necessary for the newborn's adaptation to life outside the womb.