Placental haemozoin and malaria in pregnancy

Malaria infections in pregnant women cause poor birth outcomes. Malaria pigment (haemozoin) accumulates in the placenta within macrophages and extracellularly, but its pathological significance is not understood. In order to study the potential role of haemozoin in malaria pathogenesis, we enrolled primigravid women at a Malawian government antenatal clinic and followed them through delivery. One hundred and thirteen women (71 per cent) out of 159 women followed through delivery were parasitaemic at least once. Mean placental haemozoin concentrations were significantly higher in women with delivery parasitaemias (223 ng/mg protein) than in women who never had a detectable parasitaemia (43 ng/mg protein; P<0.05), but were not significantly higher in women who were parasitaemic only during the antenatal period (67 ng/mg protein). Haemozoin was not associated with preterm delivery (PTD) or intrauterine growth retardation (IUGR) (P -values, 0.307-0.787). Thus, placental haemozoin is associated with malaria infection at the time of delivery and does not seem to be associated with poor birth outcome.