The decade of double-trouble: live birth and stillbirth sex ratio variation in Finland during the COVID-19 pandemic and Russia’s attack on Ukraine

Exogenous shocks experienced by the population like armed conflicts, natural disasters and economic downturns have all been suggested to correlate with variation in human sex ratio at birth, either through sex-specific embryonic mortality and/or primary sex adjustment. Recently experienced COVID-19 pandemic has also been related to changes in birth sex ratio in some countries but the results have been mixed. In the aftermath of the pandemic, Russia's attack on Ukraine caused further emotional anxiety and economic hardship in Europe. This was also true in Finland, which has had a decade-long close trading history with its neighboring state, Russia. Here, we examined the influence of this "double trouble" on variation in proportion of males born alive as well as male proportion of stillbirths in Finland during 2000-2024, using high-quality monthly census panel data covering the entire Finnish population (a total of 1,355,037 live births and 4,096 stillbirths). The results from Bayesian aggregated binomial time-series regressions showed no evidence for COVID-19-related associations on either the proportion of male live births or stillbirths. We did find an increased proportion of males born alive after 4 months of Russia's offensive but this finding should be considered as exploratory rather than confirmatory. If proportion of male live births or stillbirths can be regarded as a health indicator of the population, our results suggest that Finland as a society showed marked resilience in terms of non-responsive sex ratios when facing these two adverse exogenous shocks.