University University of MichiganWhen a couple is expecting a baby, it’s not just the mother that goes through hormonal changes. Previous research has suggested that men’s hormones change once they become fathers, and there is some evidence that this is a function of a decline after the child’s birth. “We don’t yet know exactly why men’s hormones are changing,” Edelstein says. “These changes could be a function of psychological changes that men experience as they prepare to become fathers, changes in their romantic relationships, or even physical changes that men experience along with their pregnant partners. The saliva samples were obtained up to four times during the prenatal period at about 12, 20, 28 and 36 weeks of pregnancy.