Umbiflow is a medical device that measures the resistance index (RI) in the umbilical cord of a foetus. Plotting the RI against gestational age, a single reading can be used to determine the level of risk of the pregnancy. This is achieved by a continuous wave Doppler apparatus consisting of a hand-held proprietary Doppler probe (transducer) with USB cable that connects to any windows-based notebook on which necessary software is installed.