A 31‐year‐old woman complained of dyspnea and orthopnea at 38 weeks of gestation. A grade 3/6 pansystolic murmur was heard, and echocardiography revealed severe mitral regurgitation with a hyperechoic obstacle on the posterior mitral valve leaflet, consistent with a diagnosis of acute heart failure due to a ruptured chordae tendineae or an infectious endocarditis. An emergency cesarean section was performed under general anesthesia. A male infant was born weighing 2928 g with Apgar scores of 7 and 8 at 1 and 5 min, respectively. The patient was managed in the intensive care unit and underwent open‐heart surgery for mitral valve repair on postpartum day 3. The two chordal tendineae appeared torn and frail, and a mitral annuloplasty was performed. No finding of infectious endocarditis was observed. Because it is a dramatic and life‐threatening clinical situation, proper diagnosis and treatment in the intensive care unit assure a good outcome for both mother and fetus.