Responsibility for the decline in fertility has traditionally been placed on women: infertility and miscarriages are attributed to their infections or immune problems, they are told to check their health, or they are blamed for an unhealthy lifestyle. However, scientists have found that in almost half of the cases the root of the problem is hidden in the male body, and the main reason is often reduced sperm quality. And although its good quality does not guarantee pregnancy, and its bad quality does not mean that the man is infertile, the chances of conception are steadily decreasing. Niels Christian Gilmuiden’s goal is not to scare the reader, but to give him food for thought and some recommendations. In his book, he summarizes basic research on sperm and comments on the influence of environment and habits on fertility and the development of diseases. Attention! The information contained in the book cannot serve as a substitute for medical advice. Before taking any recommended actions, you should consult with a specialist.