title: Placental histology in clinically unexpected severe fetal acidemia at term.
abstract: BACKGROUND
  Fetal acidemia at birth is defined as a newborn condition wherein the cord blood pH value is less than 7.0. It could represent an association with newborn brain damage; therefore, it is important to investigate which conditions precipitate its occurrence. No extensive placental analysis has been performed in cases of acidotic newborns delivered from low-risk pregnancies.
  
  
  OBJECTIVE
  To study placental characteristics in cases with severe fetal acidemia.
  
  
  METHODS
  Retrospective case-control study.
  
  
  METHODS
  34 cases, 102 controls.
  
  
  METHODS
  Umbilical artery pH was measured at delivery from a doubly clamped portion of the cord. Placental characteristics were compared between cases with severe fetal acidemia (cord pH at birth <7.0) and controls (normal pH at birth) in term low-risk pregnancies.
  
  
  RESULTS
  Macroscopic placental and umbilical cord characteristics were comparable in cases and controls whereas histological characteristics exhibited differences: diffuse villous edema, increased number of syncytial knots and villous branching abnormalities significantly affected cases more frequently than controls. Diffuse villous edema is related to fetal vascularization and associated with an increase of venous pressure; in our low-risk population, it is conceivable that these changes of fetal flow and pressure occurred in labor during the alteration of fetal heart rate. An increased number of syncytial knots and villous branching abnormalities have been previously associated with chronic placental hypoxic condition; in our low-risk population they could reflect a clinically undetectable hypoxic situation that acted during pregnancy reducing fetal resources to bear labor and delivery.
  
  
  CONCLUSIONS
  Placental histology provides useful information related to fetal acidemia in low-risk term pregnancy.
authors: Unit of Obstetrics and Gynecology, Department of Health Sciences, San Paolo Hospital Medical School, University of Milano, Milano, Italy. Electronic address: laura.avagliano@unimi.it.
authors: Laura
authors: L
authors: Avagliano
authors: Department of Obstetrics and Gynecology, FMBBM, San Gerardo Hospital, University of Milano-Bicocca, Monza, Italy.
authors: Anna
authors: A
authors: Locatelli
authors: Unit of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Spedali Civili, Brescia, Italy.
authors: Luana
authors: L
authors: Danti
authors: Department of Obstetrics and Gynecology, IRCSS Azienda San Martino, University of Genoa, Genoa, Italy.
authors: Salvatore
authors: S
authors: Felis
authors: Department of Child and Woman's Health, Careggi Hospital, University of Florence, Florence, Italy.
authors: Federico
authors: F
authors: Mecacci
authors: Unit of Human Pathology, Department of Health Sciences, San Paolo Hospital Medical School, University of Milano, Milano, Italy.
authors: Gaetano Pietro
authors: GP
authors: Bulfamante
mesh_terms: D000138:Acidosis / Q000097:blood*; D000143:Acids / Q000097:blood*; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005312:Fetal Blood / Q000378:metabolism*; D005315:Fetal Diseases / Q000097:blood*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010920:Placenta / Q000473:pathology*; D011247:Pregnancy
chemical_list: D000143:Acids
keywords: Fetal acidemia; Low-risk pregnancy; Placenta