Perinatal Physiology By Arcangela Lattari Balest, MD, University of Pittsburgh, School of Medicine Reviewed / Revised Mar 2023 View Patient Education Neonatal Bilirubin Metabolism Neonatal Cardiovascular Function Neonatal Endocrine Function Neonatal Hematopoietic Function Neonatal Immunologic Function Neonatal Pulmonary Function Neonatal Renal Function Topic Resources Normal circulation in a fetus The transition from life in utero to life outside the womb involves multiple changes in physiology and function.