ABSTRACT
Background: Conflicting evidence exists on the impact of the COVID-19 pandemic restrictions on stillbirth rates in developed countries. We aimed to examine and compare the incidence rates of stillbirth before and after the implementation of COVID-19 measures in Canada and Japan. Method(s): We conducted two populationbased studies using mother-infant linked data from JMDC hospitalizations database (JMDC Inc.) in Japan and administrative health databases in Manitoba, Canada, from October 2016 to March 2021. We used interrupted time series analysis (generalized linear models) to investigate the immediate change in level and rebound change in quarterly rates of stillbirth (fetal death > 20 weeks of gestation). We modeled the forecasted trends based on prepandemic data via autoregressive moving average models. Result(s): We included 70,931 and 169,883 pregnancies in Manitoba and Japan during the study period, respectively. On average, stillbirth rates were 0.66% in Manitoba and 0.31% in Japan. The pandemic restrictions were associated with an immediate relative increase in stillbirths in Japan by 19.19% (beta2=0.05;p=0.5693) and in Manitoba by 18.6% (beta2=0.12;p=0.4434). However, the quarterly stillbirth rates decreased (beta3=0.1625, p=0.5066) in Japan and Manitoba (beta3=0.011, p=0.8296) during the pandemic period. During the first quarter of 2021, the absolute differences in the observed and forecasted rates in Manitoba and Japan were 0.04% and -0.05%, respectively. Conclusion(s): Although various approaches were implemented to address the pandemic in Manitoba (Canada) and Japan, we found no evidence of a significant increase in the incidence of stillbirth rates during the first year of the pandemic. Healthcare services in Canada and Japan have experienced substantial changes since the start of the COVID-19 pandemic, with little influence on stillbirth rates at population level. This study will further examine the effect of the pandemic measures on other adverse pregnancy outcomes in both countries.