Development and function of oral feeding has been described. It is known that non-nutritive sucking and early introduction of oral feeding accelerate the transition from tube feeding to oral feeding. It is suggested that the preterm infant may experience a maturational lag in vagal function related to ingestive needs, which may contribute to continued feeding difficulties and may be a measurable marker of subtle neurodevelopmental problems. Both oral and nasal feeding tube may interfere with establishment of efficient oral feeding. The purpose of this study is to see whether there is a difference between oral and nasal tube feeding, regarding the institution of oral feeding.