There is conflicting evidence regarding the influence of HIV infection on the success of malaria prevention in pregnancy and effect on pregnancy outcome. The purpose of the proposed study is to assess the impact of HIV infection on the effectiveness of malaria prevention during pregnancy. This will be carried out by comparing two intermittent preventive treatments (IPTs) with sulfadoxine/pyrimethamine (SP) plus 300 mg weekly chloroquine with two doses IPT plus a weekly chloroquine placebo. The emphasis will be on assessing the effect of chloroquine on HIV viral load and malaria morbidity and foetal outcome.