Zhang 2014.

Methods	Parallel‐group randomised controlled trial
Participants	Participants: 112 preterm infants (NNS and control) Mean birth weight: 1548 grams Mean gestational age: 30.9 weeks Mean postnatal age: postnatal age was not reported but all included infants were born in other hospitals and transported within 24‐48 hours to the NICU Setting: neonatal unit, Children's Hospital of Fudan University, China Inclusion criteria: born at 29 to 34 weeks gestation, weight appropriate for gestational age, Apgar scores of > 3 at 1 minute and > 5 at 5 minutes, received all feedings by tube Exclusion criteria: congenital abnormalities (oral, heart etc.) and infants who developed chronic medical complications during NICU admission such as intraventricular haemorrhage grades III and IV, bronchopulmonary dysplasia, or necrotizing enterocolitis
Interventions	Infants were randomised to 4 groups (N = 112) Experimental group 1: NNS before gavage feeding Infants were allowed to suck on pacifiers for 5 minutes, 7‐8 times a day. The pacifier was placed in the infant's mouth whether or not they made an attempt to suck; however, where necessary the pacifier would be manipulated by the nurse to encourage sucking. NNS and oral stimulation group: the combined group was administered by the oral motor program including oral stimulation for 12 minutes and NNS for 3 minutes, once a day Experimental group 2: oral stimulation group ‐ consisted of stroking the cheeks, lips, gums, and tongues for 12 minutes All interventions took place 30 minutes prior to feeding. All interventions started 48 hours after discontinuation of nasal continuous positive airway pressure and were continued until the newborn began exclusively oral diet Experimental group 3: NNS and oral stimulation ‐ The combined group was administered by the oral motor program including oral stimulation for 12min and NNS for 3min, once a day. All infants in the three groups received the interventions 30 min before the beginning of scheduled feeding Control: no NNS Data only reported for the NNS group (experimental 1) and control group (n = 55)
Outcomes	Primary outcomes: Transition time: defined as the number of days needed from introduction of oral feeding to autonomous oral feeding Age and weight: the infants postmenstrual age and weight were recorded at the commencement of oral feeds and when autonomous oral feeding was established Secondary outcomes: Rate of transfer Feeding proficiency Volume transfer Length of stay Behavioral state: Anderson Behavioral State Scale taken at the start of each feeding session Episodes of apnoea, bradycardia, and oxygen desaturation during the final feeding session were recorded.
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"infants were randomized into one of four groups using a stratified block randomisation." No further information provided.
Allocation concealment (selection bias)	Unclear risk	Blinding of randomisation ‐ yes
Blinding (performance bias and detection bias) All outcomes	Low risk	Blinding of intervention ‐ yes Blinding of assessors ‐ yes
Incomplete outcome data (attrition bias) All outcomes	Low risk	One infant did not complete the study in the control group and 2 infants did not complete the study in the NNS group.
Selective reporting (reporting bias)	Unclear risk	Study protocol not obtained

CNS: central nervous system;NICU: neonatal intensive care unit; NNS: non‐nutritive sucking.