<prompt> On Doppler studies which is an ominous sign for IUGR fetus :Increase SD ratioReverse diastolic flowDiastolic notchAll of the above  <response>: Absence of end-diastolic frequencies or reverse diastolic flow patterns in the umbilical aery usually indicates poor perinatal outcome. Reference: Duttas Textbook of Obstetrics 7th edition page no 227 