Very high infection burden (90+ percentile) was associated with higher CRP levels, but this relationship was explained by body mass index (adjusted odds ratio (OR) 1·19; 95% confidence interval (CI) 0·95–1·50), maternal occupation (adjusted OR 1·23; 95% CI 0·98–1·55) and atopic disorders (adjusted OR 1·24; 95% CI 0·98–1·55). Here, CRP is linked to infection.