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<11.0 g/dL) although only 1.3% were severely anaemic (Hb<7 g/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.

We suggest that parity and maternal and placental malaria parasitaemia at delivery have an important negative impact on birthweight, especially in first pregnancies. This observation emphasizes the need for appropriate aggressive intervention strategies such as the use of insecticide-treated bed nets or intermittent preventive treatment to control malaria in pregnancy in the study area.

In malaria endemic areas, young children are protected against malaria attack during the first few weeks of life partially by transplacentally acquired antibodies. In this study, we show, using an in vitro assay, that part of these antibodies are involved with blocking the re-invasion of host red blood cells by erythrocytic merozoites. One hundred consecutive paired maternal-cord blood samples were collected at delivery and their plasma assayed for total IgG antibodies against crude blood stage antigens by the ELISA. The Ig fraction were precipitated from the plasma samples with (NH(4))(2)SO(4), purified on PD10 columns and used in vitro in determining the re-invasion inhibitory capacities. The mean (+/-SD) ELISA OD(405) IgG antibodies to crude blood stage antigens of maternal (0.476 +/- 0.48) and cord (0.421 +/- 0.39) plasma samples was not significantly different. However, the mean total protein concentration of the Ig fractions for maternal samples (15.82 +/- 3.85) was significantly higher (p=0.005) than that of paired cord samples (12.87 +/- 2.86 mg/ml). There was no correlation between anti-Plasmodium falciparum-specific IgG levels and total protein concentrations of the Ig fractions of both maternal and cord samples. The entire test Ig fractions were strongly inhibitory (>50 per cent) except for four paired maternal cord samples, which were moderately inhibitory (21--50 per cent) at the highest concentration tested (1:2 dilution). Furthermore, there was no correlation between maternal IgG levels and percentage re-invasion inhibition at the 1:2 dilution. The results suggest that mothers resident in malaria endemic areas possess naturally acquired re-invasion inhibitory antibodies and their foetuses can acquire these antibodies transplacentally, which may contribute to the relative protection observed in infants during their first few weeks of life.

Aim: The impact of maternal, umbilical cord and placental malaria parasitaemia on the incidence of low birthweight was investigated in pregnant women reporting for delivery at the Mutengene Maternity Centre, Fako Division, South West Province, Cameroon. Methods: The malaria parasitaemia status of 770 umbilical cords, parturient women and placental impression smears were determined by light microscopy using blood samples collected between June 1999 and September 2001. The birthweights (BW) of the newborns were recorded soon after delivery. Results: The results show that malaria parasites were present in the blood samples of 57 out of 730 (7.8%), 233/711 (32.8%) and 248/735 (33.7%) cord, maternal and placental biopsies respectively. Low birthweight (LBW) was recorded in 72 (9.6%) newborns, and the incidence was higher in primiparae. Newborns of mothers who had malaria parasites in their peripheral blood (12.4%) had a higher incidence (p=0.014) of LBW when compared with malaria parasite‐free mothers (6.8%). Similarly, neonates born from malaria‐positive placentas (13.5%) had a significantly higher incidence of LBW (p=0.006) than those from parasite‐negative placentas (6.8%). Furthermore, newborns of malaria parasite‐positive mothers, umbilical cords, placentas and primiparae had lower mean birthweight than malaria‐negative mothers, placentas, umbilical cords and multiparae. Conclusion: We suggest that parity and maternal and placental malaria parasitaemia at delivery have an important negative impact on birthweight, especially in first pregnancies. This observation emphasizes the need for appropriate aggressive intervention strategies such as the use of insecticide‐treated bed nets or intermittent preventive treatment to control malaria in pregnancy in the study area.