Mattes 1996.

Methods	Parallel‐group randomised controlled trial
Participants	Participants: 42 preterm infants Mean birth weight: 1321 grams in the control group and 1377 grams in the NNS group Mean gestational age: 30.5 weeks in the control group and 31.1 weeks in the NNS group Mean postnatal age: postconceptual age 33.7 weeks in the control group and 33.6 weeks in the NNS group Setting: NICU from across 4 general hospitals, USA Inclusion criteria: body weight greater than or equal to 1250 grams, gestational age < 34 weeks, growth parameters appropriate for gestational age, Apgar scores greater than 3 at 1 minute and greater than 5 at 5 minutes, no clinical evidence of seizure activity, grade 3 or 4 intraventricular haemorrhages, congential heart disease other than patent ductus arteriosus or peripheral pulmonic stenosis that was haemodynamically significant, respiratory distress syndrome Exclusion criteria: presence or signs of necrotizing enterocolitis, hepatic disorder, congenital infection, metabolic disease or anomalies affecting the central nervous system or gastrointestinal tract; infants with parents or guardians who were concerned that exposure could adversely influence future feeding or pacifier preference
Interventions	Experimental group 1: infants were provided with a sweetened edible pacifier for a 4 minute trial followed by a 1 minute rest and another 4 minute trial with a latex pacifier Experimental group 2: infants in the control group received their pacifiers in the reverse order. Infants were initially provided with a latex pacifier for 4 minutes, followed by a 1 minute rest, and a 4 minute trial with a sucrose flavoured pacifier. Sucking was stimulated only at the beginning of the trial by moving the pacifier in and out of the mouth 3 times. Control: no NNS. Maternal heart beat played during tube feeds Data reported for experimental group 2 and control (n = 28)
Outcomes	Anthropometric measurements Sucking measures Age at full oral feeds Sucking measures were evaluated weekly before a midday feeding. Sucking related pressures on the pacifier were translated through a pressure transducer into audio signals via a modified stereo cassette tape deck and recorded. Frequency and strength were used to assess sucking performance
Notes	Latex pacifier group used as experimental group for analysis
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised: "All infants meeting stipulated criteria were recruited at four participating hospitals." No further information provided
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 ‐ unclear
Incomplete outcome data (attrition bias) All outcomes	Low risk	Complete follow‐up ‐ yes
Selective reporting (reporting bias)	Unclear risk	Study protocol not obtained