title: Neonatal Acid-Base Status in Term Fetuses: Mathematical Models Investigating Cerebroplacental Ratio and Birth Weight.
abstract: OBJECTIVE
  Cerebroplacental ratio (CPR) is emerging as a marker of fetal hypoxia at term. The aim of this study was to demonstrate graphically the interrelationships among CPR, birthweight (BW), and neonatal pH, and construct 2D and 3D representations of the areas with potential low pH.
  
  
  METHODS
  This was a retrospective study of 2,927 term fetuses evaluated according to BW and CPR. The outcome was the acid-base status at birth. Multivariate relationships among CPR, BW, and arterial and venous pH were depicted in 3D scattergrams. Subsequently, trend surfaces were calculated and represented in 2D contour graphs. Finally, 3D representations were constructed by smothering pH data using moving average filters.
  
  
  RESULTS
  The trend surfaces and the 2D and 3D contour graphs showed the complex association among the three variables. Although pH changed with CPR and BW, the influence of the BW was smaller than the influence of the CPR, with this effect being more evident in the venous than in the arterial pH.
  
  
  CONCLUSIONS
  Two scenarios threaten fetal well-being at term: a very low birth weight and a very low fetal CPR. Our findings suggest that the importance of fetal hemodynamics in determining the acid-base status at birth surpasses that of fetal weight.
authors: Fetal Medicine Unit, St George Hospital, London, UK.
authors: José
authors: J
authors: Morales-Roselló
authors: Asma
authors: A
authors: Khalil
authors: José
authors: J
authors: Alberola-Rubio
authors: David
authors: D
authors: Hervas-Marín
authors: Maddalena
authors: M
authors: Morlando
authors: Amar
authors: A
authors: Bhide
authors: Aris
authors: A
authors: Papageorghiou
authors: Alfredo
authors: A
authors: Perales-Marín
authors: Baskaran
authors: B
authors: Thilaganathan
mesh_terms: D000136:Acid-Base Equilibrium / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D001724:Birth Weight / Q000502:physiology*; D005260:Female; D005317:Fetal Growth Retardation; D005311:Fetal Hypoxia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D008962:Models, Theoretical; D010920:Placenta / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D047929:Term Birth / Q000378:metabolism*; D016216:Ultrasonography, Prenatal; D055815:Young Adult