Prevalence and Associated Risk Factors of Malaria in the First Trimester of Pregnancy: A Preconceptional Cohort Study in Benin

[[[ Background: ]]] There is a lack of data on the burden of malaria in the first trimester of pregnancy in Africa, mainly because pregnant women generally attend the maternity clinic late. Bed nets are rarely provided to women before the second trimester of pregnancy and intermittent preventive treatment with sulfadoxine-pyrimethamine is not recommended before the second trimester, leaving women insufficiently or not protected in early pregnancy. [[[ Methods: ]]] To assess the burden of first trimester malaria, 387 women were followed up monthly from preconception to delivery. They were screened for malaria monthly from early pregnancy until delivery. A logistic multilevel model was used to assess maternal factors associated with malaria during the first trimester. [[[ Results: ]]] The proportion of women with at least 1 microscopic malaria infection during the first trimester of pregnancy was 20.8%. Women infected with malaria preconception were more likely to be infected during the first trimester (adjusted odds ratio: 2.68; 95% confidence interval, 1.24-5.78). Early gestational age was also positively correlated with malaria infection. [[[ Conclusions: ]]] Using a preconceptional study design, we showed that malaria was highly prevalent in early pregnancy. This calls for the assessment of new strategies that could protect women as soon as the first trimester.