This time we go searching for some of the root causes of male infertility with the world’s largest male offspring cohort, as we visit Bispebjerg Hospital, Copenhagen and the FEPOS-project. Though we are far from dystopian scenarios where humanity’s actual existence is threatened by infertility, it is one of the most common among major health issues facing young people. Infertility can be devastating, and half the time a couple faces infertility, semen quality is part of the problem. We sat down for a talk with Sandra Søgaard Tøttenborg, a reproductive and environmental epidemiologist, and Principal Investigator on the FEPOS-project. FEPOS investigates the possible causes of male infertility in what is passed on to the next generation at the fetal stage.  The Danish National Biobank is a treasury of science for international health research. It contains 10 million biosamples across an array of diagnostic categories, as well as the Danish Biobank Register that links over 25 million biosamples in Danish biobanks to vast amounts of register information. This podcast will give an insight into some of the amazing research done through the Danish National Biobank, and hopefully inspire researchers to utilize this potential in the future.