Impact of COVID-19 disease on placental histopathology. PLAXAVID study

The impact of COVID-19 on pregnancy has been analyzed suggesting an increased risk of placental lesions that might lead to maternal and neonatal complications. However, the current published evidence is not conclusive because contradictory results.

PLAXAVID is an observational, retrospective, histopathological, single-center study that aimed to evaluate the prevalence of vascular and inflammatory lesions in placental and umbilical cord samples of one hundred women infected by SARS-CoV-2 during pregnancy.

The histopathological analysis showed that in most of the placentas (77.8%) there were signs of maternal vascular malperfusion (MVM; primary endpoint). The most common MVM features were an accelerated villous maturation (37.4%), central villous infarcts (33.3%), and villous agglutination (46.5%). Fetal vascular malperfusion (FVM) was identified in 57.6% of samples, and the most frequent features were hyalinized avascular villi (38.4%), fetal vascular thrombi (20.2%) and umbilical cord at risk of partial obstruction (14.1%). Acute and chronic inflammatory pathology were noticed in 22.2% and 49.5% of placentas, respectively. No significant correlations were found between MVM presence and the time, duration, and severity of infection, nor with the duration of pregnancy. However, in critically ill patients, the pregnancy duration (p=0.008), newborn weight (p=0.003), and APGAR test scores (p<0.001) were significantly lower. The same trend was observed considering the presence of infection at the time of delivery and in preterm births.

A very high percentage of placentas with vascular and/or inflammatory lesions was found in the analyzed cohort. Therefore, PLAXAVID study results supported that COVID-19 should be considered a risk factor during gestation and requires close monitoring of pregnancy.