Malarial infection during pregnancy increases the risks of severe sequelae for the pregnant woman and the risk of delivering a low birthweight baby. The aim of this intervention study was to reduce significantly the prevalence of malaria parasitaemia in adolescent parturients in Matola and Boane in Mozambique. The study was focused upon the most malaria-vulnerable group, adolescent nulliparous and primiparous women. After completing the usual antenatal clinic and giving informed consent, 600 pregnant women were randomly chosen in a double blind manner to one of two regimens comparing the prevailing routine (placebo) for malaria prevention with a two dose regimen of sulphadoxine-pyrimethamine (SP). The first dose was given at enrollment with a second dose at the beginning of the third trimester. At delivery maternal and placental malaria parasitaemia as well as birthweight and gestational duration were analysed. At booking the prevalence of malaria parasitaemia was 35.3% in the placebo group and 30.6% in the SP group. At the second dose, the prevalence of malaria parasitaemia in the placebo group and SP group was 19.7% and 8.7%, respectively. This implies a relative risk (RR) of 2.24 with 95% CI (1.34, 3.75). The corresponding figures at delivery were 13.6% and 6.3% with an RR of 2.22 (1.07, 4.60) and in placenta 13.3% and 2.4% with an RR of 4.87 (1.58, 15.0). Newborns with malaria within 7 days were significantly more frequent in the placebo group, 6.4% and 0.7% respectively, with an RR of 6.55 (1.20, 35.7). Almost all (approximately 98%) of the women studied had Plasmodium falciparum, the remainder had P. malariae and P. ovale. The mean birthweight in the SP group was 3077 g and in the placebo group 2926 g. The estimated mean difference between the two groups was 151 g with 95% CI (51, 252). The mean placental weight in the placebo group was 596 and 645 g in the SP group, implying a difference of 49 g with a 95% CI (11, 88). The mean gestational duration was 6.1 days longer in the SP group, 95% CI (1.5, 10.6). In the placebo group there were two cases of urticaria and one case of nausea; in the SP group there was one case of vomiting. No newborn showed any sign of serious SP side-effect. Two doses of SP were enough to significantly reduce the prevalence of peripheral and placental malaria parasitaemia among young nulliparous and primiparous pregnant women in Matola and Boane.
