title: Relation between utero-placental and feto-placental circulations: a longitudinal study.
abstract: OBJECTIVE
  To explore the relation between total utero-placental (TQ(uta)) and feto-placental (Q(uv)) blood flows and establish longitudinal reference ranges for the TQ(uta)/Q(uv) ratio and the mean uterine artery and umbilical artery pulsatility (UtaPI/UAPI) and resistance index (UtaRI/UARI) ratios.
  
  
  METHODS
  Prospective longitudinal observational study.
  
  
  METHODS
  University hospital in Norway.
  
  
  METHODS
  Fifty-three low-risk pregnant women.
  
  
  METHODS
  Uterine artery and umbilical vein blood flow was measured using Doppler ultrasonography at 4-weekly intervals from 22(+0) to 39(+6) weeks of gestation.
  
  
  METHODS
  Ratios between utero-placental and feto-placental volume blood flows and between indices of uterine and umbilical artery impedance.
  
  
  RESULTS
  The TQ(uta)/Q(uv) ratio had a significant association with the gestational age (p < 0.00001) and decreased with advancing gestation during the second half of pregnancy. The mean UtaPI/UAPI (p = 0.094) and mean UtaRI/UARI (p = 0.323) ratios were not significantly associated with gestational age and remained relatively constant. There was no significant association between TQ(uta) and Q(uv) (p = 0.72), mean UtaPI and UAPI (p = 0.56), or mean UtaRI and UARI (p = 0.57).
  
  
  CONCLUSIONS
  The gestational-age-related changes in the utero-placental and feto-placental circulations do not appear to be affected by each other under physiological conditions. We have established longitudinal reference ranges for the utero-placental and feto-placental blood flow and impedance ratios during the second half of pregnancy.
authors: Women's Health and Perinatology Research Group, Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway. kari.flo@uit.no
authors: Kari
authors: K
authors: Flo
authors: Tom
authors: T
authors: Wilsgaard
authors: Ganesh
authors: G
authors: Acharya
mesh_terms: D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity; D005260:Female; D005333:Fetus / Q000098:blood supply*; D006801:Humans; D010920:Placenta / Q000098:blood supply* / Q000000981:diagnostic imaging; D021041:Placental Circulation / Q000502:physiology*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011446:Prospective Studies; D012016:Reference Values; D018608:Ultrasonography, Doppler; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D014471:Umbilical Veins / Q000000981:diagnostic imaging / Q000502:physiology*; D055988:Uterine Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D055815:Young Adult