A new peer-reviewed Danish study finds that a mother's exposure to toxic PFAS "forever chemicals" during early pregnancy can lead to lower sperm count and quality later in her child's life. PFAS per- and polyfluoroalkyl substances " are known to disrupt hormones and fetal development, and future "reproductive capacity" is largely defined as testicles develop in utero during the first trimester of a pregnancy, said study co-author Sandra Søgaard Tøttenborg. PFAS are a class of about 12,000 chemicals typically used to make thousands of products resistant to water, stains and heat. They are called "forever chemicals" because they accumulate in humans and the environment and do not naturally break down. A growing body of evidence links them to serious health problems such as cancer, birth defects, liver disease, kidney disease and decreased immunity. The study ... examined semen characteristics and reproductive hormones in 864 young Danish men born to women who provided blood samples during their pregnancies' first trimesters between 1996 and 2002. Mothers with higher levels of exposure more frequently raised adult men with lower sperm counts, as well as elevated immotile sperm levels, meaning their sperm did not swim. This exposure also increased the amount of non-progressive sperm " sperm that do not swim straight or swim in circles. Both issues can lead to infertility. The ubiquitous chemicals are estimated to be in 98% of Americans' blood.