Background: The evaluation of the fetal circulation, mainly of the umbilical artery (AU), middle cerebral artery (MCA) and ductus venosus (DV), have been the pillars in the diagnosis and monitoring of the main alterations in fetuses with restriction of the intrauterine growth (IUGR).Given the need to have a parameter with the predictive power of adverse outcomes that allows us to define the opportune moment of birth of a fetus with IUGR, the pulsatility index of the aortic isthmus appears as the point of connection between the two fetal circulatory systems arranged in parallel between the left and right ventricle.Objective: To establish the degree of correlation between the pulsatility index of the fetal aortic isthmus and the function of the middle left ventricle by the TEI index in fetuses with estimated fetal weight below the 3rd percentile (PFE <p3).josha.org