Effect of Sulfadoxine-Pyrimethamine doses for prevention of malaria during pregnancy in hypoendemic area in Tanzania

Abstract Background: Malaria in pregnancy increases the risk of deleterious maternal and birth outcomes. The use of ≥3 doses of sulfadoxine-pyrimethamine (SP) for intermittent preventive treatment of malaria (IPTp-SP) is recommended for preventing the consequences of malaria during pregnancy. However, the effect of IPTp-SP doses in low malaria transmission settings is not well established. This study assessed the effect of SP doses for prevention of malaria during pregnancy in low transmission settings. Methods: A cross-sectional study that involved consecutively selected 1,161 pregnant women was conducted at Mwananyamala regional referral hospital in Dar es Salaam. Assessment of the uptake of IPTp-SP was done by extracting information from antenatal clinic cards. Maternal venous blood, cord blood, placental blood and placental biopsy were collected for assessment of anaemia and malaria. High performance liquid chromatography with ultraviolet detection (HPLC-UV) was used to detect and quantify sulfadoxine (SDX). Dried blood spots (DBS) of placental blood were collected for determination of sub-microscopic malaria using polymerase chain reaction (PCR).Results: In total, 397 (34.2%) pregnant women reported to have used sub-optimal doses (≤2) while 764(65.8%) used optimal doses (≥3) of IPTp-SP at the time of delivery. The overall prevalence of placental malaria as determined by histology was 3.6%. Submicroscopic placental malaria was detected in 1.4% of the study participants. Women with peripheral malaria had six times risk of maternal anaemia than those who were malaria negative (aOR, 5.83; 95% CI, 1.10-30.92; p = 0.04). The overall geometric mean plasma SDX concentration was 10.76± 2.51μg/mL. Sub-optimal IPTp-SP dose was not associated with placental malaria, premature delivery and foetal anaemia. The use of ≤2 doses of IPTp-SP increased the risk of maternal anaemia by 1.36 fold compared to ≥3 doses (aOR, 1.36; 95%CI, 1.04-1.79; p = 0.02).Conclusion: The use of <2 doses of IPTp-SP increased the risk of maternal anemia. However, sub-optimal doses (≤2 doses) were not associated with increased the risk of malaria parasitaemia, foetal anaemia and preterm delivery among pregnant women in low malaria transmission setting. The use of optimal doses (≥3doses) of IPTp-SP and complementary interventions should continue even in areas with low malaria transmission.