Pregnancy increases the risk of malaria progression and complications with up to a 10-fold increase in the malaria case fatality rate in areas of low transmission. Sulfadoxine-pyrimethamine (SP) is used widely in Africa for the systematic intermittent presumptive, or preventive, treatment (IPTp) during the second and third trimester of pregnancy and a national program of IPTp with SP has been implemented recently in Mozambique. There is evidence that the kinetics of several other antimalarial drugs are altered in pregnancy to the extent that doses are not adequate in pregnancy, however no published study has included a pharmacokinetic component to confirm that standard doses of SP are optimal in this vulnerable patient group. This study therefore creates the opportunity to study whether the pharmacokinetic properties of SP are altered by physiological changes that occur during pregnancy.