Sample size The prevalences of severe anaemia at delivery and low birth weight have been shown to be 12% and 5.7% respectively among Gambian multigravidae who received varying doses of SP-IPT (Mbaye et al. 2006). In the absence of local data from the proposed study site, we estimate that the prevalences of severe anaemia in the third trimester and low birth weight will be 12% and 6% respectively in the LLIN +SP-IPTp arm of this study, similar to that in the Gambian population.