After experiencing morning sickness, Churchwell transforms from hapless husband to science detective. He uncovers recent research that shows men have a hormonal response during pregnancy that is synchronized with their partners. Many, if not most, men have pregnancy symptoms, ranging from dramatic mirror pregnancies to subtler weight gain. These changes may have an important evolutionary purpose in helping a man prepare emotionally for fatherhood, as well as signaling to his mate that he is bonding with her and intending to invest in their child. Finally, a man's response to pregnancy may influence a woman's own attitude and degree of maternal attachment. With Pregnant Man, Churchwell shows that men are not biological bystanders during pregnancy.