title: Betamethasone effects on ovine uterine and umbilical placental perfusion at the dose used to enhance fetal lung maturation.
abstract: OBJECTIVE
  The purpose of this study was to examine glucocorticoid effects on umbilical placental perfusion.
  
  
  METHODS
  Pregnant sheep instrumented with uterine and umbilical ultrasound transit-time flow probes received 2 doses of 12 mg betamethasone (n = 6) or saline (n = 5) intramuscularly 24 hours apart.
  
  
  RESULTS
  Maternal blood pressure and uterine flow did not change during glucocorticoid exposure. Fetal blood pressure increased, and umbilical resistance showed a transient increase after each injection (P < .05), followed by an increase of umbilical flow (P < .05) that was closely correlated to an increase in fetal heart rate (r = 0.85, P < .001), which determines cardiac output of the developing heart. Umbilical waveform indices were decreased over the entire treatment period, indicating a decrease of resistance in the fetoplacental microcirculation (P < .05).
  
  
  CONCLUSIONS
  Fetoplacental perfusion during glucocorticoid exposure is not limiting for nutrition exchange. Clinical interpretation of Doppler waveform indices needs to be interpreted with caution because they do not reflect dynamics of umbilical placental perfusion.
authors.affiliation: Department of Biomedical Sciences, Veterinary School, Cornell University, Ithaca, NY, USA. Matthias.Schwab@med.uni-jena.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Schwab
authors.forename: Turhan
authors.initials: T
authors.lastname: Coksaygan
authors.forename: Peter W
authors.initials: PW
authors.lastname: Nathanielsz
mesh_terms: D000818:Animals; D001623:Betamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D001794:Blood Pressure; D002302:Cardiac Output / Q000187:drug effects; D005260:Female; D005333:Fetus / Q000187:drug effects* / Q000502:physiology; D005938:Glucocorticoids / Q000008:administration & dosage / Q000494:pharmacology*; D006340:Heart Rate, Fetal / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects*; D008168:Lung / Q000196:embryology*; D008833:Microcirculation / Q000187:drug effects; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D012039:Regional Blood Flow / Q000187:drug effects; D012756:Sheep; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D005938:Glucocorticoids; D001623:Betamethasone