Dilli 2009.

Study characteristics
Methods	Randomised controlled trial at a single site (well‐child unit) in Turkey
Participants	158 infants ages 0 to 6 months, of which data for 70 infants aged 1 to 6 months were included in this review. Painful procedure: Multiple injections for vaccination (intramuscular or subcutaneous): Hepatitis B, bacillus Calmette‐Guérin, diphtheria‐tetanus‐pertussis and inactive polio, Haemophilus influenzae type b vaccination Study period: Not specified
Interventions	Intervention: Breastfeeding before and during vaccination Control: No intervention
Outcomes	Cry duration from time of needle insertion until all crying activity stopped NIPS score during vaccination
Notes	Power calculation: No
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"A consecutive sample of 243 infants and children age 0 to 48 months receiving routine vaccinations were randomly assigned by the first assistant to 1 of the study groups, stratified by age using sealed envelopes." (p. 386) Specific randomisation method not described.
Allocation concealment (selection bias)	Unclear risk	"A consecutive sample of 243 infants and children age 0 to 48 months receiving routine vaccinations were randomly assigned by the first assistant to 1 of the study groups, stratified by age using sealed envelopes." (p. 386) Sealed envelopes used but does not specify whether envelopes were opaque and sequentially numbered.
Blinding of participants and personnel (performance bias) All outcomes	High risk	"The mother was asked to continue breast‐feeding the infant during the procedure." (p. 386) Personnel could not be blinded to whether infant was breastfeeding or not.
Blinding of outcome assessment (detection bias) All outcomes	High risk	"The paediatrician responsible for recording the crying time and pain score was not present during the interventions and was blinded to participant’s allocation except to the breast‐feeding group." (p. 386) The researcher completing the cry time and NIPS scores could not be blinded to whether the infant was breastfeeding or not.
Incomplete outcome data (attrition bias) All outcomes	Low risk	"Four infants failed to complete the study because they did not resume feeding." (p. 386) Outcome data reported on all remaining infants. Less than 10% missing data.
Selective reporting (reporting bias)	Unclear risk	Study protocol not registered in trial registries searched.
Sample size	High risk	In the subgroup of infants aged 1 to 6 months included in this review, there were fewer than 50 infants per arm.
Other bias	Unclear risk	Children receiving subcutaneous and intramuscular injections as well as single and multiple injections included (p. 388). Unclear as to how these are broken down by intervention and control group in breastfeeding trial (only data on whole group provided).