ABSTRACT
The transition of a fetus to a newborn is perhaps the greatest physiological challenge that we must all overcome if we are to survive after birth. Two key physiological adaptations that must occur at birth are 1) the neonatal lungs must take over the role of gas exchange from the placenta and 2) the fetal circulation must transition to the newborn circulation to allow transfer of oxygenated blood from the lungs throughout the body. Importantly, lung aeration is the critical aspect of a successful transition at birth, which supports the focus of stimulating breathing and early initiation of respiratory support within the first minute of life in resuscitation guidelines worldwide. Recent preclinical and clinical studies have demonstrated the importance of initiating lung aeration prior to umbilical cord clamping, termed physiological-based cord clamping. Yet, the studies to date have not focused on the most critical of all newborns, those exposed to hypoxia in the perinatal period. This chapter outlines the mechanisms through which physiological-based cord clamping provides cardiovascular stability at birth, how hypoxia alters fetal and newborn cardiovascular physiology increasing the risk of adverse outcomes, and the potential role of physiological-based cord clamping in preventing/reducing adverse outcomes in hypoxic newborns.
