COGI 2023

EFFECT OF COVID-19 INFECTION IN PLACENTAL HISTOLOGY: ANALYSIS OF VARIANTS ACCORDING TO THE DIFFERENT PANDEMIC WAVES

Silvia Gherardi Francesca Panina Valentina Toto Anna Maria Marconi Stefania Triunfo
Department of Obstetrics and Gynecology, Milan, Italy, Asst Santi Paolo E Carlo, S. Paolo University Hospital, Universita' Degli Studi Di Milano,, Milan

Problem statement

The aim of this study was to investigate perinatal outcomes in pregnancies complicated by COVID-19, to characterize histological findings according to the different waves and vaccine uptake.

Methods

A retrospective study was designed including pregnant women affected by COVID-19. Data were collected about demographics, pregnancy course, maternal and fetal outcomes, placental biometry and macro- and microscopical morphology. . By using a temporal criterion, all waves were defined following national definition (II wave, from October to December 2020; III, from January to October 2021; IV, from November 2021 to March 2022; V, April 2022 to October 2022).

Results

A total of 239 pregnancies were included in the analysis (II wave, n=24; III, n=22; IV, n=99; V, n=94, respectively). No statistical differences were found between study groups in demographics and perinatal outcomes. Most of the patients in all groups were asymptomatic (II wave, 92%, III, 82%; IV, 93%; V, 94%, respectively). No increases in maternal complications were observed in all groups, such as diabetes or hypertensive disorders. A significant reduction of required hospitalization across the waves (II wave, 17%; III, 18%; IV, 4%; V, 3% respectively) was calculated. According to the vaccine uptake and number of dosis, a significant reduction of placental lesions was found, mainly due to the protective effect of vaccination and changes in pathogenicity of SARS-CoV2, as represented in Figg. 1 and 2. Of interest, placental findings attributable to maternal and fetal malperfusion were predominant in comparison with acute and chronic lesions, but with a significant decrease across the waves. Variants of concern also determined a decrease of chronic inflammation, although a slight increase in acute damage in placenta.

Conclusion

Across the waves of COVID-19 pandemic placental histology seems to ameliorate, with a significant reduction od adverse perinatal outcomes. A pivotal role can be played not only by vaccination, but also by changes in pathogenicity of SARS-CoV2.

Keywords: Pregnancy, COVID-19, placenta, histology, vaccine.