Inclusion Criteria:  Premature infants born 28 to 34 weeks of gestational age  Has achieved oral feeding readiness in the form of :  Stable cardiorespiratory status Fully feed through orogastric tube of 120ml/kg/day without vomiting or bloating Strong and rhythmic non-nutritive sucking (NNS), measured objectively using sucking mechanism evaluation system (5 to 10 non-nutritive sucks per burst, the repetitive pattern was stable, with a pause of 4 to 9 seconds, and the amplitude was -16.7 to -87 mmHg) Parent/guardian give consent to participate  Exclusion Criteria:  Craniomaxillofacial malformation Neonatal asphyxia with 5-minute APGAR score is less than 7 Grade 3 and 4 intraventricular hemorrhage Using endotracheal tube at the time of assessment