Malaria in pregnant women is related to low birth weight (LBW), a factor contributing to infant mortality. Which period of infection during pregnancy leads to the most harmful consequences is unclear. We analyzed data collected in Burkina Faso for 1190 pregnant women. Birth weight was analyzed through multivariate linear and logistic regressions. Infection after 6 months of pregnancy was related to a decrease in mean birth weight (-105 g, P = 0.02) and a higher risk of low birth weight (AOR = 1.8, P = 0.02). A trend was found between infection before 4 months of pregnancy and a decrease in birth weight (-68 g, P = 0.08). This suggests that the end of pregnancy is the most important period in terms of public health, but infection at the beginning of pregnancy may also have consequences. Malaria prevention policies should be started early in pregnancy, especially by implementing the systematic use of insecticide-treated nets.

Placental infection measured by placental smear at delivery is a standard indicator, widely used to characterize malaria infection in pregnant women. However, a single measure can hardly reflect the entire history of infection during pregnancy. To investigate the relation between this indicator and peripheral infection during pregnancy, we used data collected in a randomized trial of malaria prophylaxis in 928 pregnant women in Burkina Faso, 1987-1988, during which repeated measures of peripheral infection were taken. We analyzed placental infection using a logistic model, with two methods for handling missing data. Peripheral infection during two periods of pregnancy was significantly related to placental infection at delivery, before the fifth month: OR = 2.9 [1.3; 6.3]; after 7 months: OR = 4.9 [2.7; 8.8]). Therefore, an early peripheral infection may persist throughout gestation, and placental infection is a good indicator of the women's parasitological status during pregnancy.

Values in parentheses are 95% confidence intervals. Hest value = 2.37; 902 degrees of freedom; P < 0.02.

No abstract

A cohort of 570 untreated pregnant women from Burkina Faso was studied to assess the influence of epidemiologic factors on malaria infection, which was quantified as the mean of serial, season-adjusted parasitemia measuremects (mean parasite density [MPD]) carried out during the last five months of gestation. A significant effect of the area of maternal residence on the MPD was found ( P < 0.003) and was probably. due to geographic differences in mosquito transmission conditions. The strong relationship observed between parity and malaria infection ( P < O.OOOl), with MPD levels decreasing as the number of gestations increased, confirms that primigravidae are a high-risk group whose protection should be a priority. After adjustment for two relevant epidemiologic factors (i.e., area of residence and parity), the residual MPD values fitted a mixture of two distributions. This result supports the view that a major gene is involved in the determination of malaria infection intensities and is consistent with the results of a recent familial study in Cameroon.