Monthly Analysis of Infant Mortality Rate in Portugal during the COVID-19 Pandemic: Insights from Continuous Monitoring.

Introduction: The COVID-19 pandemic significantly impacted global public health. Infant mortality rate (IMR), a vital statistic and key indicator of a population's overall health, is essential for developing effective health prevention programs. Existing evidence primarily indicates a decrease in IMR during the COVID-19 pandemic. We conducted a national-level analysis to calculate IMR and describe its course over the years (from 2016 until 2022), using a month-by-month analysis.

Methods: Data on the number of deaths under one year of age was collected from the Portuguese E-Death Certification System (SICO), and data on the number of monthly live births was obtained from Statistics Portugal. The IMR was calculated per month, considering the previous 12 months' cumulative number of deaths under one year of age and the number of live births.

Results: In Portugal, the IMR decreased before and during the COVID-19 pandemic. The lowest values were observed in September and October 2021 (2.15 and 2.14 per 1000 live births, respectively). The IMR remained below the threshold of three deaths per 1000 live births during the pandemic's critical period.

Conclusion: Portugal has achieved remarkable progress in reducing its IMR over the last 60 years. The country recorded its lowest-ever IMR values during the COVID-19 pandemic. Further studies are needed to fully understand the observed trends.