van Eijk AM, et al. - In this systematic review and meta-analysis, researchers examined how markers of sulfadoxine-pyrimethamine resistance in Plasmodium falciparum are associated with the efficacy of sulfadoxine-pyrimethamine intermittent preventive treatment during pregnancy (IPTp) for malaria-associated outcomes. Outcomes of this meta-analysis of aggregated data from 57 clinical studies indicated clear reductions in the effectiveness of sulfadoxine-pyrimethamine IPTp to avert low birthweight and other outcomes such as malaria infection at delivery and maternal anemia, in correlation with increases in the prevalence of two molecular markers of sulfadoxine resistance. Association of sulfadoxine-pyrimethamine IPTp with a significant but modest protective effect against low birthweight was observed in areas with 90% or higher prevalence of P falciparum dhps Lys540Glu mutation and with less than 10% prevalence of sextuple-mutant parasites. However, in areas where sextuple-mutant parasites are common (pooled prevalence estimate 37%), no protection was achieved with sulfadoxine-pyrimethamine IPTp against low birthweight.