Ultrasound is a technology that works similarly to the way bats use echoing sound waves to fly and hunt at night. Ultrasounds within the context of pregnancy and birth are used to get information by creating images of the baby, the baby or placenta’s blood flow, or listening to the baby’s pulse. The ultrasound wand that is placed on your belly sends a beam of fast (ultra) sound waves at the baby which then bounces off of the baby’s body and back to the beam. The sonogram machine turns that information into an image of the baby. The Doppler technology turns it into an audible rhythm (and sometimes an image) of the baby’s pulse.