Countdown: How Our Modern World is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race Shanna H. Swan by Scribner, $37, 292 pages) Fertility rates have been declining precipitously globally but especially in the west over the past few decades. In Countdown, Shanna Swan, an environmental and reproductive epidemiologist, explores the health and cultural [...]