The fetal heart rate is faster that the normal heart rate of an ault. The younger the fetus the faster the rate. In middle and late pregnancy the fetal heart beat can be heard almost anywhere over the uterus depending on the position of the fetus. In the first trimester of pregnancy the fetal heart may be detected with an ultrasound machine. The sound is asynchronous and different from the maternal pulse that may be detected and heard in the nearby arteries (uterine arteries), called uterine souffle.