Respiratory Infant Mortality Rate by Month of Birth in Mexico.

BACKGROUND: Respiratory syncytial virus (RSV) is a major contributor to severe Acute Respiratory Infections (ARI) in infants worldwide, leading to significant morbidity and mortality. The seasonal nature of RSV and other respiratory infections presents unique risks, especially for infants in low- and middle-income countries, such as Mexico, where comprehensive RSV surveillance is limited. This study aims to analyze respiratory infant mortality rates by month of birth across Mexico, with a focus on identifying high-risk periods and regional differences. METHODS: National birth and mortality data from the Instituto Nacional de Estadística y Geografía were analyzed for all infants born between April 2014 and March 2020. Respiratory mortality rates (based on ICD-10 J and U codes) were calculated by month of birth and examined across eight geographical regions in Mexico. Mortality trends were analyzed using descriptive statistics to assess seasonal and regional variations. A correlation analysis was conducted between respiratory mortality and confirmed RSV hospitalization data to assess the temporal relationship between increased mortality and epidemic activity of this virus. RESULTS: A total of 12,604,902 live births were recorded in Mexico during the study period, with 8805 infant deaths attributed to respiratory causes, resulting in a respiratory infant mortality rate of 0.7 deaths per 1000 births. Mortality rates exhibited strong seasonal patterns, with infants born between September and November at higher risk of respiratory death, peaking in October. The highest mortality rates were observed in the South region, while the lowest rates were in the Northeast. CONCLUSIONS: These findings highlight the importance of implementing preventive strategies in Mexico that are aligned with regional RSV seasonality. Timing preventive interventions with regional and seasonal mortality trends should enhance the cost-effectiveness and impact of RSV immunization programs, ultimately reducing infant mortality nationwide.