Effect of Indoor Residual Spraying on Malaria in Pregnancy and Pregnancy Outcomes: A Systematic Review.

Malaria in pregnancy increases maternal and perinatal morbidity and mortality. Indoor residual spraying (IRS) is a core vector control strategy used to reduce transmission in endemic areas; however, its efficacy in reducing the sequelae of malaria in pregnancy is not well described. PubMed, Embase, Cochrane, and Web of Science were searched for all studies assessing IRS exposure during pregnancy. Abstracts and full texts were reviewed independently by two researchers, with discrepancies adjudicated by a third. Of 3,319 studies that met the search criteria, 17 met the inclusion criteria. Thirteen studies reported on the effect of IRS on malaria endpoints during pregnancy, five on birth outcomes, and one on a fetal anomaly. Twelve of the 13 studies exploring maternal malaria and 3 of 3 studies reporting on placental malaria demonstrated a reduction among those exposed to IRS during pregnancy. Results were more mixed for obstetric outcomes. Two of the best-quality studies showed reductions in preterm birth, low birthweight, and fetal/neonatal mortality; a third high-quality study did not demonstrate a reduction in perinatal mortality but did not evaluate preterm birth. One study found a significantly increased risk of preterm birth in those exposed to IRS, although the study was of lower quality. A final study demonstrated a small, although statistically significant, association between IRS and male urogenital birth defects. In malaria-endemic areas, the published literature suggests that IRS during pregnancy reduces the incidence of malaria parasitemia. However, without high-quality prospective studies directly examining IRS in pregnancy, the impact on birth outcomes is less clear.