Marco is a driving instructor based in Paris, who leads a relatively normal life with his fiancée, Irène de Fontenoy, a talented hairdresser, and their young son, Lucas. Their life takes an unexpected turn when they enjoy a chicken dinner and attend a Mireille Mathieu concert together. During the concert, Marco suddenly suffers a dizzy spell, prompting them to leave early. Back at home, Irène becomes increasingly worried about Marco's health and urges him to see a doctor, but he initially dismisses her concerns, attributing his discomfort to indigestion from the chicken.
The following morning, Marco visits Dr. Delavigne to seek medical advice. To everyone’s surprise, the doctor diagnoses Marco with symptoms typically associated with pregnancy, which leads her to refer him to a gynecologist for further tests. As the investigation unfolds, Marco, curious and a bit bewildered, purchases strawberries and a textbook on female anatomy—reminding Irène of her own cravings when she was pregnant with Lucas, which raises her suspicions.
The next day, during a drive to Dr. Chaumont’s office, Marco confesses to Irène that he is, in fact, pregnant. This revelation causes Irène to faint from shock. At Dr. Chaumont’s clinic, the doctor confirms the diagnosis and explains that hormones from the chicken have caused an imbalance, making Marco sufficiently feminine to carry a child. She advises Marco to follow a low-sodium diet and to avoid strenuous activities for the next seven months.
Marco, trying to process this bizarre situation, returns to his job at a driving school and confides in his colleague, Lucien Soumain. Irène, meanwhile, discusses the extraordinary news with her coworkers and clients, highlighting how their lives are about to change forever. Later, the couple gathers the courage to tell Lucas about the pregnancy, sharing the incredible secret with their son.
As news of Marco’s pregnancy spreads, he is contacted by Scipion Lemeu [– the director of a maternity clothing company], who proposes an unusual advertising campaign. Lemeu offers to pay the couple ten thousand francs per month, along with paid vacations, to model a new line of paternity clothes, until their child turns ten. Marco’s pregnancy becomes a worldwide sensation, even drawing the attention of major newspapers like The New York Times, which describe his condition as “the most important event since man walked on the Moon.”
Marco is showcased at an International Medical Congress, where Dr. Chaumont introduces him to an audience of doctors. During a panel discussion, Marco, Irène, and several medical professionals, including Dr. Delavigne and Dr. Chaumont, along with journalist Ferdinand Delabut and Pastor Petit, debate topics such as the rise of pregnant men, women’s liberation, and contraception—highlighting the social and scientific implications of this unprecedented phenomenon.
As the situation escalates, numerous reports surface across France of men experiencing pregnancy symptoms, igniting concerns over overpopulation. The film features two different endings: In the original French version, Marco is diagnosed with hysterical pregnancy, which brings sorrow to both him and Irène. However, during their wedding, Irène faints again but then joyfully reveals that she is pregnant, symbolizing hope and new beginnings. In the alternate Italian ending, Marco realizes he has been misdiagnosed and unexpectedly goes into labor at his wedding, although the baby is not shown. Following these events, the phenomenon spreads, and men everywhere begin experiencing pregnancy symptoms, raising questions about society, gender roles, and human biology on a grand scale.
