Bernbaum 1983.

Methods	Parallel‐group randomised controlled trial
Participants	Participants: 30 preterm infants Birth weight < 1500 grams (inclusion criteria) Mean gestational age: 31.5 weeks Mean postnatal age: 10 days Setting: the Children's Hospital of Philadelphia, USA. Inclusion criteria: infants with a birth weight < 1500 grams, with no requirement for surgical intervention, no seizures or CNS haemorrhages, no cardiac or pulmonary diseases and no requirement for further management from the intensive care team at the time nasogastric feeding commenced Exclusion criteria: premature infants that were small for gestational age
Interventions	Experimental group: pacifier during gavage feeding. Sucking opportunities were not allowed between feeding periods. The pacifier which was constructed from an unperforated standard‐sized disposable nipple plugged with the plunger of a 20 mL syringe to prevent swallowing of air. Caregivers manipulated it to encourage sucking and placed it so that it remained in the infant's mouth during the entire feeding. All infants were gavage fed until they attained a weight of 1700 grams, at which time they began oral feedings that increased in frequency and amount according to the infant's tolerance. Control: no NNS Sucking opportunities were not allowed between feeding periods in either group.
Outcomes	Intraoral negative (sucking) pressures measured via a specially designed nipple that was attached to pressure transducer. Sucking patterns: classified into two categories: organized uninterrupted sucks or bursts greater than 3 consecutive sucks; sporadic sucking described as sucks associated with bursts. Daily caloric intake Anthropometric measures (weight, length and head circumference) Gastrointestinal transit time: determined by the time interval between the nasogastric feed with 125 mg of Carmine red and its appearance in the stools Frequency of bowel movements Time taken until first 5 bottle feeds are achieved Time to reach 2 kg weight Days for transition from partial to full oral feeds Length of hospital stay
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random envelope assignment (information supplied by author)
Allocation concealment (selection bias)	Low risk	Blinding of randomisation ‐ yes
Blinding (performance bias and detection bias) All outcomes	High risk	Blinding of intervention ‐ noBlinding of outcome assessors ‐ not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	Complete follow‐up ‐ yes
Selective reporting (reporting bias)	Unclear risk	We were unable to obtain the study protocol.