Statistical analysis
TfR
We computed HAZ and BAZ using WHO AnthroPlus with WHO 2007 growth reference for 10–19 years girls. Data analysis was conducted with SAS 9.4 (SAS Institute Inc.) and STATA (StataCorp., v.13.0). The primary analysis of the treatment effect was intention-to-treat analysis with multiple imputations of missing endline outcome variables (The outcome variables were Hb, body iron stores and the adjusted log-transformed PF, TfR and RBP. We estimated the differences in post-intervention measurements between the two groups with adjustment for baseline values of each measurement as in an ANCOVA, using a linear mixed model (Proc Mixed) in SAS. In the analysis, the school was included as a random intercept. We did not transform Hb and body iron stores, which were normally distributed. Adjustments for covariates did not influence our results and were subsequently dropped.We estimated the post-intervention prevalence differences