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Ultrasound Obstet Gynecol. 2018 Oct 18. doi: 10.1002/uog.20150. [Epub ahead of print]

The cerebral-placental-uterine ratio as a novel predictor of late fetal growth restriction: a prospective cohort study.

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Mercy Perinatal, Mercy Hospital for Women, Melbourne, Victoria, Australia.
Department of Obstetrics and Gynaecology, University of Melbourne, Victoria, Australia.
Translational Obstetrics Group, University of Melbourne, Victoria, Australia.



Fetal growth restriction (FGR) is a major risk factor for stillbirth and most commonly arises from uteroplacental insufficiency. Despite clinical examination and third trimester fetal biometry, cases of FGR often remain undetected antenatally. Placental insufficiency is known to be associated with altered blood flow resistance in maternal, placental, and fetal vessels. We evaluated the performance of individual, and combined Doppler blood flow resistance measurements for the prediction of term FGR.


This was a prospective study of fetal growth including Doppler measurements in 347 nulliparous women at 36 weeks' gestation. We analysed the pulsatility indices (PI) of the uterine arteries (UtA), umbilical artery (UA), and fetal vessels, individually and in combination, for prediction of birthweights <10th , <5th and <3rd centiles. We compared Doppler parameters' sensitivities, positive and negative predictive values, and odds ratios (OR) for these birthweights at ~90% specificity. We also analysed the correlations between Doppler measurements and other parameters of placental insufficiency - fetal growth velocity and neonatal body fat.


The Doppler combination most strongly associated with placental insufficiency was a newly generated parameter which we have named the cerebral-placental-uterine ratio (CPUR). The CPUR is the cerebroplacental ratio (middle cerebral artery PI/UA PI) divided by the mean UtA PI. The CPUR detected FGR better than the mean UtA PI or the cerebroplacental ratio (CPR) alone. At ~90% specificity, a low CPUR had sensitivities of 50% for birthweight <10th centile, 68% for <5th centile, and 89% for <3rd centile. This was compared to respective sensitivities of 26%, 37% and 44% for a low CPR, and 34%, 47% and 67% for a high mean UtA PI. Low CPUR predicted birthweight <10th centile with an OR of 9·1, <5th centile with an OR of 17·3, and <3rd centile with an OR of 57 (P<0·0001 for all). The CPUR also correlated most strongly with fetal growth velocity and neonatal body fat measures.


In this cohort, our novel Doppler combination - the cerebral-placental-uterine ratio (CPUR; CPR/UtA PI) - had the strongest associations with placental insufficiency. The CPUR detected more FGR than any other Doppler parameter measured. If independently replicated, this new parameter may lead to better identification of fetuses at increased risk of stillbirth that may benefit from obstetric interventions. This article is protected by copyright. All rights reserved.


Cerebral-Placental-Uterine Ratio (CPUR); Cerebroplacental ratio (CPR); Doppler; Fetal growth restriction ; Placental insufficiency; Small-for-gestational-age; Ultrasonography; Uterine artery; prenatal


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