Background: Malaria and HIV are associated with preterm births possibly due to partial maternal vascular malperfusion resulting from altered placental angiogenesis. There is a paucity of data describing structural changes associated with malaria and HIV coinfection in the placentae of preterm births thus limiting the understanding of biological mechanisms by which preterm birth occurs.

Objectives: This study aimed to determine the differences in clinical characteristics, placental parenchymal histological, and morphometric features of the terminal villous tree among women with malaria and HIV coinfection having preterm births.

Methods: Twenty-five placentae of preterm births with malaria and HIV coinfection (cases) were randomly selected and compared to twenty-five of those without both infections (controls). Light microscopy was used to determine histological features on H&E and MT-stained sections while histomorphometric features of the terminal villous were analyzed using image analysis software. Clinical data regarding maternal age, parity, marital status, level of education, gestational age and placental weight were compared.

Results: Placental weight, villous perimeter and area were significantly lower in cases as compared to controls 454g vs. 488g, 119.32μm vs. 130.47μm, and 937.93μm² vs. 1132.88μm² respectively. Increased syncytial knots and accelerated villous maturity were significantly increased in the cases. The relative risk of development of partial maternal vascular malperfusion was 2.1 (CI: 1.26-3.49).

Conclusion: These findings suggest that malaria and HIV coinfection leads to partial maternal vascular malperfusion that may lead to chronic hypoxia in the placenta and altered weight, villous perimeter and surface area. This may represent a mechanism by which malaria and HIV infection results in pre-term births.