Malaria infection in pregnancy and its effects on haemoglobin levels in women from a malaria endemic area of Fako Division, South West Province, Cameroon

Abstract

Anaemia in pregnancy has been associated with maternal morbidity and mortality and is a risk factor for low birthweight. The importance of malaria as a major cause of anaemia in pregnancy in malaria endemic areas has not been fully elucidated. In two cross-sectional studies of pregnant women at antenatal enrolment and at delivery, we determined the prevalence of anaemia and assessed some risk factors associated with anaemia such as malaria parasitaemia and parity, in women from a malaria endemic area of south western Cameroon. Of the 1118 women whose Hb levels were analysed at first antenatal enrolment, 68.9% were anaemic (Hb < 11.0g/dL) although only 1.3% were severely anaemic (Hb < 7g/dl). At delivery, 69.9% (485/694) of the parturient women were anaemic with 4.3% having severe anaemia. The mean haemoglobin (Hb) level of the pregnant women at enrolment and at delivery was not significantly different. The mean Hb level of malaria parasite positive pregnant women (P = 0.0001) and parturient women (P = 0.0001) were significantly lower than those who were malaria parasite free. Similarly, the mean Hb level of primigravidae at antenatal enrolment (P = 0.0001) and at delivery (primiparae; P = 0.0001) was markedly lower than that of multigravidae or multiparae, respectively. Of the anaemic cases, 52.1% were malaria positive while 47.9% were malaria free at enrolment. By contrast, 36.9% (179/485) of the anaemic cases were associated with maternal malaria parasitaemia while 37.3% (174/466) were associated with placental malaria parasitisation. Thus at delivery, anaemia was more common in women without malaria parasitaemia (P = 0.0003) or whose placentas were malaria free (63.1% vs 36.9%; P < 0.05). The prevalence of anaemia was significantly higher (OR = 2.399; P = 0.001) in mothers whose peripheral blood and placental biopsy were free of malaria parasites (69.9%) than in those whose peripheral and placental samples had malaria parasites. The mean birthweight and placental weights of newborns of mothers with and without anaemia were similar. In addition, there was no association between maternal anaemia and the incidence of low birthweight. Our study demonstrates a high prevalence of mild to moderate anaemia amongst the study population with relatively low incidences of severe anaemia. Furthermore, at delivery > 50% of the anaemic cases were not associated with maternal or placental malaria parasitaemia suggesting the existence of other causes of anaemia in this community. This observation is important in developing a strategy for controlling anaemia in the community.