Prenatal ultrasound is a taken-for-granted component of modern maternity care, to such an extent that most obstetrician-gynecologists find it impossible to practice their profession without it. American women now routinely undergo four to five ultrasounds per pregnancy. Despite the absence of demonstrated benefits, there is also a trend toward “new applications of ultrasound…at earlier stages in pregnancy” (p. 47), including Doppler fetal heart rate monitoring that magnifies the unborn baby’s exposure manyfold.