Although blood flow in the placental vasculature is governed by the same physiological forces of shear, pressure
and resistance as in other organs, it is also uniquely specialized on the maternal and fetal sides. At the materno-fetal
interface, the independent uteroplacental and umbilicoplacental circulations must coordinate sufficiently to supply the fetus
with the nutrients and substrates it needs to grow and develop. Uterine arterial flow must increase dramatically to accommodate
the growing fetus. Recent evidence delineates the hormonal and endothelial mechanisms by which maternal
vessels dilate and remodel during pregnancy. The umbilical circulation is established de novo during embryonic development
but blood does not flow through the placenta until late in the first trimester. The umbilical circulation operates in the
interest of maintaining fetal oxygenation over the course of pregnancy, and is affected differently by mechanical and
chemical regulators of vascular tone compared to other organs. The processes that match placental vascular growth and fetal
tissue growth are not understood, but studies of compromised pregnancies provide clues. The subtle changes that cause
the failure of the normally regulated vascular processes during pregnancy have not been thoroughly identified. Likewise,
practical and effective therapeutic strategies to reverse detrimental placental perfusion patterns have yet to be investigated.
Keywords: Blood flow regulation, vasculature, placental insufficiency, compromise, pregnancy.
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