AN EVALUATION OF THE EFFECTS OF INTERMITTENT SULFADOXINE-PYRIMETHAMINE TREATMENT IN PREGNANCY ON PARASITE CLEARANCE AND RISK OF LOW-BIRTH-WEIGHT IN RURAL MALAWI

The prevalence of infection with malarial parasites and the incidence of anaemia and delivery of infants with low birthweight (LBW) were inv estigated in 575 Malawian mothers who received one, two or three doses of sulfadoxine-pyrimethamine (SP) during pregnancy. All the subjects were enrolled at their first antenatal visit and all delivered at hosp ital. The prevalence of Plasmodium falciparum infection at first anten atal visit was 35.3% in primigravidae and 13.6% in multigravidae (P<0. 001). Mean haemoglobin concentration was significantly lower in primig ravidae than in multigravidae (8.8 v. 9.5 g/dl; P<0.001). Of the 233 w omen tested for HIV infection, 18.8% of the primigavidae and 23.7% of the multigravidae were seropositive. At delivery, there was no signifi cant difference in parasite prevalence in peripheral or placental bloo d between women who had received one or two antenatal doses of SP. The multigravidae who had received two doses of SP had higher mean haemog lobin concentrations than those who had received just one (P=0.009) [t his difference was not seen in the primigravidae (P=0.92)]. However, l inear regression analysis indicated that the haematinic supplements gi ven to the subjects contributed more to this increase in haemoglobin c oncentration than the SP. The mean birthweights were higher, and incid ence of LEW lower in babies born to primi- and multi-gavidae who had r eceived two or three doses of SP treatment than those seen in babies b orn to women who had had just one dose (P<0.03 for each). The odds rat io for LBW in primigravidae compared with multigravidae decreased from 3.2 to 1.0 as the number of SP doses increased from one to three. The benefit of three doses (compared with none) was equivalent to the pop ulation-attributable risk of LEW in primigravidae being reduced from 3 4.6% to 0%. Subjects who were seropositive for HIV were twice as likel y to give birth to LEW babies as the other subjects. The use of SP was not associated with maternal side-effects or perinatal complications. The present results indicate that multiple doses of SP taken during p regnancy will lead to a highly significant reduction in the incidence of LBW in infants born to primigravidae, even if the women have HIV in fections. This reduction is observable even when parasite prevalence a t delivery is high because of re-infections in late pregnancy; reducti on in parasite prevalence earlier in pregnancy, as the result of SP tr eatment, leads to improved foetal growth.