Gastric Emptying During the Labour

Each participant will be placed on a table, in the semi-recumbent position with elevation of the head at 45° and a first ultrasound examination will be performed. After that, the participant will be invited to eat a test meal (flavoured yoghurt) in 5 minutes. An ultrasound examination of the antrum allowing measurement of the antral area will be performed at 15, 60, 90 and 120 minutes after the end of the ingestion of the test meal. The participant must stay in the semi-recumbent position during the total duration of the study. The non-invasive ultrasound measurement, of the antral cross-sectional area is performed using a Sonosite ultrasound equiped with a 2 -5.5MHz probe. The diameters (longitudinal D1 and anteroposterior D2) of the antrum are measured in the sagittal plane passing by the abdominal aorta and the left lobe of the liver. The value of the antral cross-sectional area is given by the formula : Antral area = π x D1 x D2 / 4.