Pain below the left rib cage in pregnant women is commonly caused by the following: first, improper posture: the abdominal pressure will be too great when the pregnant woman is lying down, so she will prefer to lie on her side. If the left side lying position is too long, it will cause continuous pressure on the local tissues, thus producing the clinical symptoms of pain below the left rib cage, and the pain will be more obvious when pressed. Second, left-sided intestinal distension: the patient will have severe digestive tract dysfunction, exhaustion and defecation will also be affected, and eating will be severely difficult, mainly related to the increased pressure in the abdominal cavity. The intestinal peristalsis slows down, the intestine produces gas accumulation, and the patient will have clinical manifestations of pain under the left rib cage, which can improve the clinical symptoms after timely position change as well as appropriate walking. Therefore, pregnant women with left-sided subcostal pain must be treated as soon as possible to avoid serious adverse consequences.