This article critically examines the constitution of impairment in prenatal testing and screening practices and various discourses that surround these technologies. While technologies to test and screen (for impairment) prenatally are claimed to enhance women's capacity to be self-determining, make informed reproductive choices, and, in effect, wrest control of their bodies from a patriarchal medical establishment, I contend that this emerging relation between pregnant women and reproductive technologies is a new strategy of a form of power that began to emerge in the late eighteenth century. Indeed, my argument is that the constitution of prenatal impairment, by and through these practices and procedures, is a widening form of modem government that increasingly limits the field of possible conduct in response to pregnancy. Hence, the government of impairment in utero is inextricably intertwined with the government of the maternal body.