Turnabout by Thorne Smith

Sally Willows envied her adman husband his glamorous work; Tim Willows felt Sally lived in ease and luxury while he was sweating to pay the bills. So an ill-tempered minor god, tired of their bickering, worked a modest miracle... Sally Willows, now occupying her husband’s body, experienced the full horrors of the Nationwide Advertising Agency, while Tim, now outwardly Sally, dealt with the amourous advances of a local Lothario. It was a toss-up whether Sally/Tim’s well-earned dismissal or Tim/Sally’s bizarre attempt at murder was more spectacular—but both seemed insignificant when Tim found he was pregnant!