The Zero Trimester explores why the task of perfecting pregnancies now takes up a woman's entire reproductive life, from menarche to menopause. Miranda R. Waggoner shows how the zero trimester rose alongside shifts in medical and public health priorities, contentious reproductive politics, and the changing realities of women's lives in the twenty-first century. Waggoner argues that the emergence of the zero trimester is not simply related to medical and health concerns; it also reflects the power of culture and social ideologies to shape both population health imperatives and women's bodily experiences.