All pregnant women who attended antenatal clinics were screened for malaria antigens with OptiMAL dipsticks. Those with a positive antigen test were considered eligible, and after informed consent had been obtained from them 5mls of venous blood was drawn from an antecubital vein for baseline measurements of haemoglobin, white blood cell counts (total and differential), bilirubin, alanine aminotransferase, aspartate aminotransferase and gamma-glutamyl transferase and for making filter paper blood spots. Women were then assessed clinically and obstetrically with the view to enrolling them into the study. Pregnancy viability and gestational age were confirmed with ultrasound scanning by the study clinician or the principal investigator. Pregnant women with positive malaria antigen tests confirmed microscopically were randomised into four treatment arms if they satisfied all inclusion criteria.