In Malawi, the standard of care to prevent malaria during pregnancy at the time of the study was a two dose sulfadoxine-pyrimethamine intermittent protective treatment (SP IPT) regimen administered in the second and third trimester of pregnancy. In this investigation, this two dose strategy was compared to a monthly SP regimen. The objective for the study was to determine the efficacy of the different regimens for HIV positive and HIV negative women in the prevention of placental malaria.