From Fetus to Neonate: A Sensational Journey

The transition from fetus to neonate is a period marked by intense changes - physiologic, anatomic, and biochemical. Some of these changes must occur immediately while others can evolve over a more protracted time span. However, failure of some vital changes to ensue has resulted in negative, sometimes fatal consequences. Of all the facets of transition to extrauterine life the most immediately vital changes occur in the cardiorespiratory system. This article presents a review of information necessary to understand the transition from fetal to neonatal life: fetal circulation, the pulmonary vascular bed, transition from fetal to neonatal circulation, stages of transition, and the cycle of events that occur when transition is disrupted.