In the early 1990s, scientists discovered that sperm counts in industrialized countries had declined precipitously over the previous half century. It turns out that the incidence of other reproductive health problems beyond male infertility also increased in the latter part of the 20th century and into the 21st century. With us to discuss human reproductive health, and how it has changed in part due to exposure to pollutants, is Shanna Swan. Shanna received her BS in mathematics at the City College of New York, her MS in biostatistics at Columbia University, and her PhD in statistics at the University of California, Berkeley. She specializes in Environmental and Reproductive Epidemiology, and is a Professor of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai, New York. Shanna investigates how prenatal and early childhood exposure to stressors, including chemicals commonly found in the environment, impact the reproductive health and development of children. Today we discuss her new book published by Scribner & Sons – the book is called Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Health, and Imperiling the Future of the Human Race.