AimInfections can impair cognitive development, but their role on adverse childhood educational outcomes is unknown. We examined the associations of infectious morbidity and inflammatory biomarkers with grade repetition and school absenteeism.MethodsWe followed 2762 Colombian children aged 5-12 years for a school year. We quantified inflammatory biomarkers at enrolment and prospectively recorded incidence of gastrointestinal and respiratory infections, doctor visits and absent days from school using pictorial diaries. We estimated adjusted relative risks (ARR) with 95% confidence intervals (CI) for grade repetition and absenteeism by infectious morbidity burden and inflammatory biomarker categories, and percentages of the associations mediated through absenteeism.ResultsMorbidity was associated with increased risk of grade repetition. ARR (95% CI) of grade repetition comparing high versus no incidence of gastrointestinal, respiratory and ear infections were, respectively, 2.17 (1.00, 4.72), 2.31 (1.28, 4.16) and 2.57 (1.13, 5.86). Infections also predicted school absenteeism, which mediated 35%, 31% and 38% of the corresponding morbidity-grade repetition associations. Elevated white blood cells (WBC), especially granulocytes, were related to increased grade repetition and school absenteeism risks.ConclusionChildhood infections and elevated WBC are associated with grade repetition and school absenteeism. Absenteeism does not fully explain the morbidity-grade repetition associations.