Background: This study evaluated admissions with severe community-acquired pneumonia (CAP) with pleural effusion (PE) in a pediatric university hospital and the impact of the increased average municipal human development index (M-HDI) in the local incidence of the disease in the last decade. Methods: This is a retrospective longitudinal study of patients (0–13 years old) with CAP. The municipal human development index (M-DHI) of the place of residence of patients was obtained. We calculate the crude odds ratios (ORs) of variables related to risk of developing PE. The variables that reached a significance level of 80% (P < 0.20) were selected for multivariate analysis. The logistic regression model was used for the selection of the parsimonious model, according to the likelihood ratio. Results: The 465 patients’ ages ranged from 1 to 174 months. The median of age (months) in children with PE was 36.00; in children without the PE was 29.00 (P < 0.011); media of variation in M-HDI in the period in patients with PE was 0.767 ± 0.002 and in patients without PE was 0.778 ± 0.002 (P < 0.001). In the logistic regression model, the absence of comorbidity (OR = 2.909) and the HDI < 0.770 (OR = 3.015) were predictive factors associated with PE. Conclusion: The progressive increase of the M-DHI during the study period, although to a slightly higher level, was correlated with the reduction in the number of admissions with CAP with PE