Table 1. Risk of bias for randomized and quasi-randomized studies.

	Azad 2010	Bhutta 2008	Bhutta 2011	Manandhar 2004	Tripathy 2010
Random sequence generation (selection bias)	+	?	+	+	+
Allocation concealment (selection bias)	+	+	+	+	+
Blinding of participants and personnel (performance bias)	-	?	?	-	-
Blinding of outcome assessment (detection bias)	-	-	+	+	+
Incomplete outcome data (attrition bias)	+	?	?	+	+
Selective reporting (reporting bias)	+	+	+	+	+
Other bias	+	-	+	+	-

+: low risk of bias, -: high risk of bias,?: unclear