Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk
Allocation concealment (selection bias)	Low risk	Quote: “…conducted in the intervention community, Nkongsamba, and in the comparison community, Mbalmayo” Comment: unit of allocation was by community/city
Similar baseline characteristics	High risk	Quote: “Girls in the sample from Mbalmayo are more likely to be able to read and more likely never to have been married than are the girls in the sample from Nkongsamba.” Comment: baseline characteristics were not similar
Similar baseline outcome measurement	High risk	Comment: baseline outcome measurements were not similar
Blinding of participants and personnel (performance bias)	Unclear risk
Blinding of outcome assessment (detection bias)	Unclear risk
Incomplete outcome data (attrition bias)	Unclear risk	Comment: insufficient information to permit judgement
Prevention of knowledge of allocated intervention	Unclear risk	Comment: insufficient information to permit judgement
Protection against contamination	Low risk	Comment: allocation was done by community
Selective reporting (reporting bias)	Unclear risk	Comment: insufficient information to permit judgement and no protocol was found
Other bias	Low risk	Comment: study appears free from other bias