Men with shorter Anogenital Distance have lower sperm counts

In male rodents, anogenital distance (AGD) –the distance form the anus to the genitals–reflects the pups exposure to testosterone and other androgens during prenatal development and also predicts later reproductive
success. These results, from a study of young healthy men living in Rochester NY, suggest that this is also true in young healthy men and that the androgenic environment during early fetal life exerts a fundamental
influence on both AGD and adult sperm counts in humans, as demonstrated in rodents