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The effects of maternal position, in late gestation pregnancy, on placental blood flow and oxygenation: An MRI study

Couper, S; Clark, A; Thompson, JMD; Flouri, D; Aughwane, R; David, AL; Melbourne, A; ... Stone, PR; + view all (2020) The effects of maternal position, in late gestation pregnancy, on placental blood flow and oxygenation: An MRI study. Journal of Physiology 10.1113/JP280569. (In press).

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Abstract

KEY POINTS: Maternal supine sleep position in late pregnancy is associated with an increased risk of stillbirth. Maternal supine position in late pregnancy reduces maternal cardiac output and uterine blood flow. Using MRI, this study shows that compared to the left lateral position, maternal supine position in late pregnancy is associated with reduced uteroplacental blood flow, oxygen transfer across the placenta with an average 6.2% reduction in oxygen delivery to the fetus and an average 11% reduction in fetal umbilical venous blood flow. ABSTRACT: Maternal sleep position in late gestation is associated with an increased risk of stillbirth though the pathophysiological reasons for this are unclear. Studies using MRI have shown that compared with lateral positions, lying supine causes a reduction in cardiac output, reduced abdominal aortic blood flow and reduced vena caval flow which is only partially compensated for by increased flow in the azygos venous system. Using functional MRI techniques, including an acquistion termed Diffusion-Relaxation Combined Imaging of the Placenta (DECIDE), which combines diffusion weighted imaging and T2 relaxometry, blood flow and oxygen transfer were estimated in the maternal, fetal and placental compartments when subjects were scanned both supine and in left lateral positions. In late gestation pregnancy, lying supine caused a 23.7% (p <0.0001) reduction in total internal iliac arterial blood flow to the uterus. In addition, lying in the supine position caused a 6.2% (p = 0.038) reduction in oxygen movement across the placenta. The reductions in oxygen transfer to the fetus, termed delivery flux, of 11.2% (p = 0.0597) and in fetal oxygen saturation of 4.4% (p = 0.0793) did not reach statistical significance. It is concluded that even in healthy late gestation pregnancy, maternal position significantly affects oxygen transfer across the placenta and may in part provide an explanation for late stillbirth in vulnerable fetuses. This article is protected by copyright. All rights reserved.

Type: Article
Title: The effects of maternal position, in late gestation pregnancy, on placental blood flow and oxygenation: An MRI study
Location: England
DOI: 10.1113/JP280569
Publisher version: http://dx.doi.org/10.1113/JP280569
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: magnetic resonance imaging, maternal position, placental oxygenation, pregnancy
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL EGA Institute for Womens Health
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL EGA Institute for Womens Health > Maternal and Fetal Medicine
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng
URI: https://discovery.ucl.ac.uk/id/eprint/10118472
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