A randomized, double-blind, placebo-controlled trial, which compared the effects of three interventions (weekly chloroquine prophylaxis, daily iron and weekly folic-acid supplementation, and case management of malaria) on congenital malaria, maternal haemoglobin (Hb) and foetal outcome, was conducted among primigravidae resident in Hoima district, Uganda. Among 473 babies examined at birth or within 7 days of birth, 198 (42%) were parasitaemic, the level of parasitaemia in an infant being strongly correlated with those of placental (P< 0.01) and maternal, peripheral parasitaemia (P < 0.01). However, 33 (17%) of the parasitaemic babies were born to mothers who had placental but not peripheral parasitaemia, 22 (11%) to mothers who had peripheral but not placental parasitaemia, and 12 (6%) to mothers with neither peripheral nor placental parasitaemia. Overall, 163 babies were each examined for malarial parasites at birth and 1 month later. Of the 76 (47%) found to have parasitaemia at birth, 37 (23%) appeared aparasitaemic at the 1-month follow-up but 28 (17%) were still parasitaemic at that time. Among the babies born to the mothers who only received case management of malaria during pregnancy, parasitaemia at birth was associated with infant anaemia at birth (i.e. < 140 g Hb/litre; P = 0.03). Infants found to be parasitaemic at the 1-month follow-up had lower mean concentrations of Hb at that time than their aparasitaemic counterparts (P= 0.03). Parasitaemia at birth was not significantly associated with low birthweight, in any of three intervention groups. The intervention given to the mother had no significant effect on the parasitaemia of her baby, either at birth or at the age of 1 month. Congenital malaria per se may have little influence on birthweight but may have an impact on infant anaemia. In conclusion, congenital parasitaemia was not associated with birthweight, but was related to anaemia at birth in infants born to women who had only received active case management during their pregnancies.