(C-035) Does COVID-19 relate to adverse maternal outcomes? Risk of cesarean section and preterm birth among Japanese women with COVID-19 during pregnancy.

Background: The COVID-19 pandemic has heavily impacted the health of many people globally as well as maternal and neonatal outcomes. During the pandemic, pregnant women represented the vulnerable group in society as COVID-19 was believed to have caused several health complications resulting in heightened susceptibility to infections during pregnancy.

Objectives: The study examined whether COVID-19 during pregnancy is associated with adverse maternal outcomes, including cesarean delivery and preterm birth in Japanese pregnant women.

Methods: A retrospective cohort analysis was conducted, using data from DeSC claims database collected between March 2019 and October 2022. The study included a total number of 8,002 Japanese pregnant women who were between the ages of 15 and 60 at the time of childbirth and stratified into two groups, with and without a definitive COVID-19 diagnosis. The primary outcomes included preterm birth and cesarean section. Risks of having adverse outcomes at the time of giving birth were assessed and stratified by gestational age.

Results: The number of pregnant women whose delivery date was available was 8,002. Out of them, the pregnant women with definitive COVID-19 diagnosis were 52, and the ones without definitive COVID-19 diagnosis were 7,950. The cesarean section was performed in 19.2% of the pregnant women with COVID-19 diagnosis and 7.2% of the pregnant women without COVID-19 diagnosis, with a risk ratio (RR) of 2.7 (95% CI; 1.5-4.7) with a statistical significance (p=0.004). The proportion of preterm births was also significantly higher, specifically among those infected after considering preterm birth classification by gestational age (p=0.045). The proportion of preterm births in 22-36 gestational weeks for diagnosed mothers was also slightly higher (30.8%) than pregnant women without COVID-19 diagnosis (26.7%). To narrow it even further, late preterm birth (32-36 weeks) occurred in 25.0% of pregnant women with COVID-19 diagnosis and in 25.6% of pregnant women without COVID-19 diagnosis. Very preterm birth (28-31 weeks) occurred in 1.9% of pregnant women with COVID-19 diagnosis and in 1.2% of pregnant women without COVID-19 diagnosis. Finally, extremely preterm birth (22-27 weeks) occurred in 3.9% of pregnant women with COVID-19 diagnosis and in 0.7% of pregnant women without COVID-19.

Conclusions: The findings based on this study suggest that there is a relationship between having COVID-19 during pregnancy and adverse maternal outcomes such as preterm birth and cesarean delivery. These results emphasize the need for enhanced health monitoring in pregnant women, and vaccination prioritization for them to minimize the risks of this disease. The impact of COVID-19 may be greater during early gestational age.