Background　Rapid assessment of the properties and volume of gastric contents in the third trimester of pregnancy with bedside ultrasound is important for obstetricians to gain information to predict the possibility of the regurgitation and aspiration of gastric contents during labor, and to prepare for its intervention.　Objective　To review gastric ultrasound as a valid method to evaluate the volume of gastric contents in the third trimester of pregnancy, and to predict the regurgitation and aspiration of the gastric contents during labor.　Content　The regurgitation of gastric content is not rarely seen during the third trimester of the pregnancy because of changes in hormone, gastrointestinal function, and body mass. During labor, the regurgitation could increase risk of aspiration of gastric content, resulting in infectious pneumonia. The prognosis is associated with the volume, and physical and chemical properties of gastric contents. Bedside ultrasound is an invasive, convenient, and effective diagnostic means that is useful to identify gastric contents in pregnant women. This article review the method to accurately make qualitative and quantitative estimation of gastric contents with ultrasound in different body positions and at particular section levels.　Trend　Bedside ultrasound can be used to evaluate gastric contents in the third trimester of pregnancy. Further investigations are warranted to standardize the method.