The mean haemoglobin (SD) concentration at the end of the malaria transmission season was slightly higher in children in the SP group [10.8 (1.7) g/dL ] compared to the placebo group [10.6 (1.8)g/dL ], difference 0.23 (0.002,0.45) P = 0.048 (adjusted for baseline Hb and other covariates) but this difference is unlikely to have been clinically significant. This evidence concerns the gene GSTM1 and malaria.