(695) Increased Chronic Inflammation of the Placenta in COVID-19-Infected Pregnant Patients

COVID-19 infection during pregnancy has been linked to adverse birth outcomes, potentially due to increased inflammation. This study compared placental inflammation in individuals with COVID-19 infection during pregnancy to placentas of those who delivered prior to the pandemic to understand inflammation associated with COVID-19 infection and timing.

Study Design:

Participants were enrolled in the Stress, Pregnancy, and Health study from 2018-2022. Placentas were collected < 2 hours from delivery and histologically examined. Medical records were manually reviewed for evidence of COVID-19; infection timing, severity, symptoms, vaccination status were abstracted for those infected. The control group included placentas from births before December 1, 2019. Models were adjusted for maternal age, race/ethnicity, and socioeconomic characteristics.

Results:

Among the 605 participants, 57 had confirmed COVID-19 infections and 214 delivered before December 1, 2019. Of the 57 positive cases, 5(8.7%) were asymptomatic, 39(68.4%) mild, 1(1.7%) severe, and 6(10.5%) did not have documented symptoms. Those infected with COVID-19 during pregnancy had increased odds of high-grade placental chronic inflammation (OR=2.23, CI 1.06-4.69), particularly amongst those infected before 20 weeks gestation (OR=3.57, CI 1.25-10.18). Prevalence of chronic basal villitis was higher in those infected with COVID-19 (p< 0.001). There were no significant differences in acute inflammation (p=0.169), fetal vascular pathology (p=0.488), or maternal vascular pathology (p=0.255) between the infected and uninfected cohorts.

Conclusion:

In a cohort of predominantly mild COVID-19 infections during pregnancy, COVID-19 was associated with increased odds of placental chronic inflammation, driven primarily by chronic basal villitis. Inflammatory patterns differed by timing of infection, with increased odds of chronic placental lesions among those infected early in pregnancy. These findings enhance understanding of COVID-19 infection's inflammatory effects in pregnancy, aiding in prevention and treatment of at-risk pregnant patients.