98 Uneke: Effects of placental malaria on perinatal outcome of glucose and oxygen that would have gone to the fetus. Histopathological studies of in- fected placentas have found thickening of the cytotrophoblastic membranes, which may in- terfere with nutrient transport [35,46]. Although IUGR is more common than PTD with chronic placental infection, chronic infection of the placenta (with pig- ment and parasites) may be associated with LBW, through both prematurity and IUGR [26,47]. Active placental infections were as- sociated with a statistically significant lower risk of LBW as a result of IUGR and with a non-significant increase in the risk of LBW as a result of prematurity [26]. This finding suggests that acute infections toward the end of pregnancy may play an important role in the induction of PTD, consistent with higher rates of abortions and preterm deliveries that have been observed during malaria transmis- sion seasons [48]. Because premature infants are more likely to die than IUGR babies, the prevention of placental malaria particularly toward the end of gestation in malarious areas becomes absolutely imperative [49]. Effects on Neonatal Anthropometric Parameters Neonatal anthropometric parameters such as neonatal length, head circumference, and placental weight have been related to placental malaria. In southeastern Tanzania, chronic ongoing malaria infection of the pla- centa was associated with significant reduc- tions in mean head circumference, neonatal length, and body index (weight/length), whereas past infections were associated only with reduced mean length at birth [26]. In southeastern Nigeria, a slightly higher pro- portion of infected placenta was not signifi- cantly associated with lower neonatal length and lower head circumference; in the Ubangi district of Zaire, malarious placentas had no consistent relationship with neonatal length or head circumference (Uneke et al., unpublished data) [24]. Reduction in new- born length and head circumference associ- ated with chronic infections probably indicates a prolonged effect on fetal nutri- tion, which previously has been suggested [49,50]. Similarly, it has been suggested that the reduction in the body mass index may reflect the severity and duration of fetal mal- nutrition [26]. Two earlier studies evaluated the rela- tionship between placental malaria and pla- cental weight in Gabon. The mean weight of term placentas with malarial changes was significantly less than that of placentas with- out such changes [51,52]. In southeastern Nigeria, placental malaria was significantly associated with lower placental weight (Uneke et al., unpublished data). The reason for this reduction is not fully known, but it may be associated with changes in the pla- centa, including the presence of parasitized erythrocytes and malarial pigment particles in the intervillous space, chronic basal villi- tis, malarial pigment deposits in the tro- phoblasts, trophoblastic damage with focal necrosis, partial loss of microvilli, and thick- ening of the trophoblastic basement mem- brane [53]. As a result of these changes, a high density of parasites and chronic para- site infection in the placental blood and the associated cellular immune response may result in consumption of glucose and oxygen that would have gone to the fetus [35]. Pla- cental insufficiency also could be attributa- ble to physical blockage by parasitized red blood cells and the massive monocyte infil- tration of the intervillous spaces. Such infil- trate is likely to be a source of cytokines, including interferon-g, interleukin-2, inter- leukin-6, and tumor necrosis factor–a, which are considered detrimental to pregnancy be- cause they are associated with growth retar- dation [54]. Fetal anemia The prevalence of fetal anemia, defined as cord hemoglobin level < 12.5g/dl, is re- portedly very high in sub-Saharan Africa. In two separate studies conducted in southern Malawi, fetal anemia prevalences of 23.4 percent [55] and 23.3 percent [56] were recorded, while in Maputo Mozambique, up to 93 percent of newborns were found to have fetal anemia [57]. Interestingly, a sta- tistically significant link was established be- tween fetal anemia and maternal malaria infection in all of these studies. The contrib-