Background: Pregnant women living in an area of stable malaria transmission such as Lagos, Nigeria, have been
identified as being at an increased risk of the effects of malaria infection. In this area, most of the infections are
asymptomatic which means they are overlooked and untreated much to the detriment of the mother and her
foetus. The reality of scaled-up malaria interventions with long-lasting insecticide treated nets, vector control,
artemisinin combination therapy (ACT) and intermittent preventive treatment of malaria pregnancy (IPTp) using
sulphadoxine pyrimethamine (SP) is that it is also essential to determine the risk factors at play in these kinds of
circumstances. This study was aimed at identifying the factors associated with risk of malaria infection in pregnant
women in Lagos, Southwest Nigeria.
Methods: Demographic information and malaria prevention practices of the pregnant women studied were
captured using structured questionnaire. Microscopy was used to establish malaria infection, species identification
and parasite density. Relative risk and multivariate logistic regression analysis were used to compare factors
associated with malaria in pregnant women.
Results: Malaria microscopy details, demographic information and malaria prevention practices of the pregnant
women were obtained using a structured questionnaire. The prevalence of malaria using peripheral blood from
1,084 pregnant women that participated in the study was 7.7%. Plasmodium falciparum (P. falciparum) was seen in
95.2% of the cases as either mixed infection with P. malariae (3.6%) or as a mono infection (91.6%). Malaria
preventive practices associated with a significant reduction (P<0.05) in the malaria infection was the use of
insecticide sprays (RR = 0.36, 95 C.I. 0.24-0.54), and the combined use of insecticide spray and insecticide-treated
nets (ITN) (RR= 6.53, 95% C.I. 0.92-46.33). Sleeping under ITN alone (RR = 1.07, 95% C.I. 0.55-2.09) was not associated
with significant reduction in malaria infection among the study participants with malaria parasitaemia. Young
maternal age (<20years) (RR = 2.86, 95% C.I. 1.48 – 5.50), but not primigravidity (RR = 1.36, 95% C.I. 0.90-2.05), was
associated with an increased risk of malaria infection during pregnancy. After a multivariate logistic regression,
young maternal age (OR = 2.61, 95% C.I. 1.13 – 6.03) and the use of insecticide spray (OR = 0.38, 95% C.I. 0.24-0.63)
were associated with an increase and a reduction in malaria infection, respectively.
Conclusion: Malaria prevalence was low among the pregnant women studied. Young maternal age and non-usage
of insecticidal spray were the main factors associated with an increased risk of malaria infection among pregnant
women in Lagos, Nigeria.