Cong 2011.

Methods	Randomized cross‐over trial
Participants	28 preterm infants (PMA 30‐32 weeks): 18 infants — 80 min SSC (Study a); 10 infants — 30 min SSC (Study b) Postnatal age, mean ± SD, days: 5 ± 1 (Study 1); 6 ± 2 (Study 2) Birth weight, mean ± SD, grams: 1779 ± 277 (Study 1); 1577 ± 327 (Study 2) Painful procedure: heel lance Study period: unclear
Interventions	Intervention: (a) Study a: 60 minutes of skin‐to‐skin care before heel stick, with continued SSC during procedure, and followed by 20 minutes SSC post‐procedure; (b) Study b: 10 minutes of skin‐to‐skin care before heel lance, with continued SSC during procedure, and followed by 20 minutes SSC post‐procedure Control: standard care during painful procedure Provider: mother
Outcomes	PIPP score, salivary and serum cortisol at baseline, heel warming, heel stick and recovery.
Notes	Country: United States Power calculation: yes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	“permuted block randomization to determine the order of condition (KCH or IH first) was used. A list of randomization codes with four subjects in each randomization block using the SAS(R) procedure PLAN was developed by an independent statistician."
Allocation concealment (selection bias)	Low risk	“The list of random codes consisted of the subject’s number and assignment to groups; assignments were kept in sealed envelopes and opened in front of the mother after consent was obtained."
Blinding (performance bias and detection bias) All outcomes	Unclear risk	“A video camera recorder was set up and focused on the infants’ faces to record facial actions. The videotapes were independently scored by the researcher and one other certified PIPP scorer (trained to reliability by the PIPP creator), who was blind to the purpose of the study.” "Another limitation is that the PIPP scorers could not be blind to KCH because maternal respiratory movements moved the infant’s face up and down in the video, as previously reported and acknowledged by other KC pain researchers." Potential for bias as researcher coded videos and it is unknown if data were collected by the same individual
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data were provided for all infants recruited in the study
Selective reporting (reporting bias)	Low risk	All outcomes were reported in Tables 1‐2 and Figures 1‐2
Other bias	Low risk	“Standard incubator care for 24 hr was considered a sufficient “wash out” period because physiological and behavioural state effects of KC disappear within 3 hr of KC cessation.”