Every year in France, 60,000 children are born prematurely (before 37 weeks of amenorrhea - WA), and present an immaturity of their various systems, in particular the digestive system. This can result in feeding intolerance, expressed by abdominal distension, regurgitation, irregular transit and abdominal discomfort. It can influence the length of hospitalization and lead to necrotising enterocolitis, a major complication. At the Clermont-Ferrand University Hospital Center, abdominal massages have been performed by physiotherapist for several years in order to improve the state of the digestive system of preterm infants. The indication for abdominal massages are very dependent on the caregivers in charge of the newborns because the evaluation of feeding intolerance remains subjective. In this context, the investigators carried out a first study to validate a scale that they created (ECAP scale : Clinical Assessment Scale for Abdominal state of Preterm infant) to assess in a rapid, reliable and reproductible manner the abdominal state of preterm infant - data currently being published). This scale can pose the indications for abdominal massage more objectively. The hypothesis is that abdominal massage improves feeding tolerance (decrease ECAP score), allows faster weight gain and reaching the full ration and therefore reduces the length of hospitalization of preterm infants. The aim of the study is to assess the effectiveness of abdominal massage, over a period of 14 days, on the feeding tolerance of preterm infants (under 34 weeks of amenorrhea), defined by the achievement and maintenance of an ECAP score less than 4 during 3 days.