BackgroundThis study determined the rate of mother-to-child transmission (MTCT) of HIV among HIV positive women with placenta malaria and factors associated with placenta malaria.MethodsThis was a prospective observational study of booked HIV positive pregnant women in labour. A smear for malaria parasite was made from blood taken from the placental tissue post-delivery. The baby HIV testing was done with DNA polymerase chain reaction at 6 weeks postpartum. Data on age, parity, gestational age, religion, address, highest educational attainment and knowledge about malaria prevention in pregnancy was obtained with questionnaires and analysed using SPSS version 20. The P-value was set at 0.05 providing a confidence interval of 95%.ResultsA total of 174 booked HIV women participated in this study. The placental malaria parasitaemia prevalence was 44.8%. Overall rate of MTCT of HIV infection was 17.2%. Number of infants with HIV infection among women with maternal placental malarial parasitaemia was 30/78 (38.5%), while it was 0/96 (0%) for women without placenta malaria. There was significant relationship between placenta malaria density and infant HIV status (P-value = 0.001). The relative risk for MTCT of HIV for women with placenta malaria Density > 5000 was 25% with 95% confidence interval of 11.41–54.76%.ConclusionThe mother-to-child transmission rate of HIV was high among HIV positive women with placental malaria parasitaemia. There is the need to review the malarial treatment and prophylactic measures at least in this group of women and to establish the nature of relationship between placenta malaria and MTCT of HIV infection.