PATIENTS AND METHODS From July 1, 2005 to Dec 31, 2006, a prospective masked randomized control trial will be conducted at the level III Neonatal Intensive Care Unit (NICU) of eight neonatal centers in Taiwan. Study is approved by Institutional Review Board (IRB) of each hospital. Preterm VLBW infants (birth weight < 1500 gm) who were enterally fed are eligible for the trial. They are randomized into the study or control group by a random number table sequence after informed parental consents were obtained. The allocations are contained in opaque sequentially numbered and sealed envelopes. Preterm VLBW infants who have severe asphyxia (stage III), fetal chromosome anomalies, fetal cyanotic congenital heart disease, congenital intestine atresia, gastroschisis and omphalocele were excluded.