Malaria in pregnancy is a major cause of maternal and newborn morbidity and mortality in sub-Saharan Africa]. Effective antimalarial preventive and treatment regimens can significantly reduce malaria-related morbidity and mortality in the mother and baby. However, therapeutic choices are limited by concerns about possible toxicity to the fetus and because of these concerns pregnant women are normally excluded from clinical trials. This, combined with the lack of adverse events reporting system, results in a scarcity of data on drug safety and efficacy in pregnancy. Moreover, changes in the maternal physiology in pregnancy often alter the pharmacokinetic of drugs. Artemether-lumefantrine (ALN) is a highly efficacious artemisinin-based combination therapy approved by the World Health Organisation for use in the 2nd and 3rd trimesters, although it is still infrequently used in pregnancy and there is uncertainty as to the optimum dose. The pharmacokinetics of ALN are altered in pregnancy, resulting in reduced plasma concentrations and while the standard adult dose is still effective in high transmission settings, where pregnant women have higher levels of immunity, efficacy is reduced significantly in low transmission settings where women have lower levels of immunity. Inadequate antimalarial treatment dosing in pregnancy risks treatment failure or breakthrough infection and exposure of malaria parasites to sub-therapeutic drug concentrations thus selecting for drug resistance.