Diestrus is a stage in the reproductive cycle of female mammals, occurring after estrus and before anestrus. During this phase, which typically lasts about two months, the body prepares for a potential pregnancy. If fertilization does not occur, the body will eventually return to the anestrus phase. In diestrus, the ovaries produce hormones like progesterone, which helps maintain the uterine lining. This phase is crucial for those species that have a defined breeding season, as it allows for the possibility of gestation if mating has taken place.