title: Proximity of term labor deepens the fall of Doppler impedance in the fetal cerebral arteries.
abstract: OBJECTIVE
  To determine the existence of Doppler changes in the fetal vertebral, middle cerebral and umbilical arteries prior to term labor.
  
  
  METHODS
  Five hundred and twenty eight Doppler examinations of the vertebral (VA), middle cerebral (MCA) and umbilical (UA) arteries resistance indices (RI) were performed between 37 and 41 weeks gestation. For each artery, values were converted into multiples of the median (MoM) and were divided into four groups according to the interval to labor and compared using Kruskal-Wallis tests. Subsequently, values were plotted in scattergrams and linear regressions and 95% confidence intervals were calculated. Finally, using multivariate analysis and model averaging, the importance and interrelationship of Doppler measurements in the explanation of the interval to labor was evaluated.
  
  
  RESULTS
  Univariate and multivariate analysis confirmed that, independently of gestational age, fetuses examined close to labor presented more intense Doppler changes in the cerebral arteries with a significant reduction of the VA RI and MCA RI. This reduction was larger in the MCA. No significant changes were detected in the UA.
  
  
  CONCLUSIONS
  Before the onset of term labor, the fetal cerebral flow presents an additional reduction of impedance, which is more intense in the MCA system.
authors.affiliation: Servicio de Obstetricia y Ginecología, Hospital Universitario y Politécnico La Fe , Valencia , Spain and.
authors.forename: José
authors.initials: J
authors.lastname: Morales-Roselló
authors.forename: David
authors.initials: D
authors.lastname: Hervás-Marín
authors.forename: Alfredo
authors.initials: A
authors.lastname: Perales-Marín
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007743:Labor, Obstetric / Q000502:physiology*; D016014:Linear Models; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000502:physiology; D015999:Multivariate Analysis; D011247:Pregnancy; D011263:Pregnancy Trimester, Third / Q000502:physiology*; D047929:Term Birth; D018615:Ultrasonography, Doppler, Color; D016216:Ultrasonography, Prenatal / Q000379:methods; D014469:Umbilical Arteries / Q000000981:diagnostic imaging* / Q000502:physiology; D014711:Vertebral Artery / Q000000981:diagnostic imaging* / Q000502:physiology