Increasing evidence has linked childhood pneumonia with early exposure to ambient air pollution. However, the impact of exposure to air pollutants before birth is unclear.To further clarify whether exposure to a particular pollutant during preconceptional and prenatal periods, may pose a higher risk of developing childhood pneumonia.This case-control cohort study consisted of 1510 children aged 0-14 years in Changsha, China between 2017 and 2019. Data of children's history of pneumonia and blood biomarkers were obtained from the XiangYa Hospital records. Each child's exposure to air pollutants, including nitrogen dioxide (NO), sulfur dioxide (SO), and particulate matter with an aerodynamic diameter ≤ 10 µm (PM), was calculated using data from ten air pollution monitoring stations. A multivariate logistic regression model was used to quantify the relationship between childhood pneumonia and exposure to ambient air pollution during the preconceptional and prenatal periods.Childhood pneumonia was significantly associated with preconceptional and prenatal exposure to the industrial-related air pollutant, SO, for 1 year before conception, for 3 months before conception and for the entire pregnancy, with ORs(95% CI)= 4.01(3.17-5.07), 4.06(3.29-5.00) and 6.51(4.82-8.79). Also, children who were sick with pneumonia had higher white blood cell and neutrophil counts, and children with low eosinophil count or hemoglobin are likely to get pneumonia. Sensitivity analysis showed that boys, and children in high temperature area were susceptible to the effect of both preconceptional and prenatal exposure to industrial SO.Preconceptional and prenatal exposure to industrial-related air pollution plays a significant role in the incidence and progression of childhood pneumonia, supporting the hypothesis of "(pre-)fetal origin of childhood pneumonia".