Abstract
Background: Pneumonia is the leading cause of death and hospitalization among young children worldwide, but its risk factors are not clear. Objective: To examine the effect of maternal exposure to diurnal temperature variation (DTV) during preconceptional and prenatal periods on childhood pneumonia.Methods: A retrospective case-control study was conducted for pneumonia (N=699) and normal (N=811) children under age of 14 who were enrolled in the Xiangya Hospital, Central South University, Changsha, China. Demographic data (gender, age, birth season, gestational weeks, parity, mode of delivery, and parental atopy) were collected from the hospital's electronic medical records system. We calculated the individual DTV exposure during different time windows. The relationship between maternal exposure to outdoor DTV and pneumonia in children was analyzed by logic regression models.Results: Pneumonia in children was linked to outdoor DTV exposure during one year before conception (adjusted OR=2.53, 95% CI:1.56-4.10), during entire pregnancy (adjusted OR =1.85, 95% CI:1.24-2.76), and the first and second trimesters, with statistical significance. Sensitivity analysis showed that boys exposure to outdoor DTV during prenatal period were at higher pneumonia risk than girls.Conclusions: Preconceptional and prenatal exposure to DTV plays an important role in the development of childhood pneumonia, the first and second trimesters were the key exposure timing-windows.