As evidence supports the link between oxidative stress and female infertility in humans [51–53], the upregulation of ALDH5A1 and GSTM3 in PWBC suggests that a greater presence of ROS species in the blood stream may reduce the likelihood of pregnancy success to AI in beef heifers, but do not prevent the heifers from becoming pregnant to a bull later in the breeding season. This evidence concerns the gene ALDH5A1 and female infertility.