Fetal Physiology and the Transition to Extrauterine Life

Clin Perinatol. 2016 Sep;43(3):395-407. doi: 10.1016/j.clp.2016.04.001. Epub 2016 Jun 11.


The physiology of the fetus is fundamentally different from the neonate, with both structural and functional distinctions. The fetus is well-adapted to the relatively hypoxemic intrauterine environment. The transition from intrauterine to extrauterine life requires rapid, complex, and well-orchestrated steps to ensure neonatal survival. This article explains the intrauterine physiology that allows the fetus to survive and then reviews the physiologic changes that occur during the transition to extrauterine life. Asphyxia fundamentally alters the physiology of transition and necessitates a thoughtful approach in the management of affected neonates.

Keywords: Fetal physiology; Intrauterine circulation; Transition from intrauterine to extrauterine life; Transition physiology.

Publication types

  • Review

MeSH terms

  • Adaptation, Physiological*
  • Ductus Arteriosus / physiology
  • Female
  • Fetus / physiology*
  • Foramen Ovale / physiology
  • Heart / embryology
  • Heart / physiology*
  • Humans
  • Infant, Newborn / physiology*
  • Lung / embryology
  • Lung / physiology*
  • Parturition
  • Pregnancy
  • Pulmonary Circulation / physiology