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Updated: Jun 10, 2026
The 4-vessel Sampling Approach to Integrative Studies of Human Placental Physiology In Vivo
Published on: August 2, 2017
Relation between utero-placental and feto-placental circulations: a longitudinal study
Kari Flo1, Tom Wilsgaard, Ganesh Acharya
1Women's Health and Perinatology Research Group, Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway. kari.flo@uit.no
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.
Design:
Prospective longitudinal observational study.
Setting:
University hospital in Norway.
Population:
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.
Main Outcome Measures:
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).
Conclusion:
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.
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