Sosa 1976a.

Methods	Randomized controlled trial (random numbers in sealed envelopes).
Participants	60 healthy full‐term infants and their mothers randomized immediately after delivery.
Interventions	1) Experimental group = mothers held their infants in SSC for 45 min after the episiotomy repair. They were encouraged to breast feed. 2) Control group = infants were separated from their mothers for 12 hours. All women had episiotomy (hospital routine for primiparous women). No woman had analgesia during labor.
Outcomes	1) Mean duration of breastfeeding. 2) Episodes of illness, growth and development, mortality.
Notes	Study was done with poor, urban primipara from the marginal area of Guatemala city. We have reported on results for the Roosevelt 1 study as Sosa 1976a. This study was conducted at a charity hospital in 1974 when women who moved from rural to urban areas were just beginning to deliver in a hospital and more of these poorer women ended up in the control group and were more likely to breast feed. The socio‐economic index score (includes home environment, education and income) of women in the control group was 11 and in the experimental group was 14 so the groups were unbalanced as far as socio‐economic status was concerned.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	“Assignment of mother‐infant pairs.... was made from random numbers..”
Allocation concealment (selection bias)	Unclear risk	Allocations were concealed in sealed envelopes which were opened immediately after delivery.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding of outcome assessors is not mentioned, apart from blinding of researchers for behavior outcomes measured in a different population in a 3‐armed investigation of maternal bonding. For this study staff were likely to have been aware of treatment group and may have altered other aspects of treatment.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Behavior outcomes were collected by blinded research staff; however, outcome assessors also accompanied the mothers home from hospital so may well have been aware of group allocation.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	60 women. Denominators for longer‐tem outcomes were not specified so it is not clear how many women remained available to follow‐up at each data collection point.
Selective reporting (reporting bias)	High risk	No SD reported with mean breastfeeding duration. No systematic reporting of longer term outcomes for all trials collected at 3, 6, 9 and 12 months.
Other bias	High risk	More women in the control group of this trial had poor socio‐economic status as measured with a socio‐economic index score. The authors report a P < 0.05 with no further details. The authors have no evidence but guess that women in the control group for this trial were more likely to be from the countryside where breastfeeding continues for 2 years. There is no way to verify this explanation of the difference in breastfeeding status favoring the control group.