Placental histological differences between COVID19 infected and non-infected mothers during third trimester of pregnancy: a retrospective cohort study.

BACKGROUND

Covid-19 infection was revealed to be associated with higher risk of maternal and fetal morbidity and mortality. Knowing that Covid-19 virus can infect the placenta, the aim of this study is to investigate placental histological differences between Covid-19 uncomplicated pregnancies and Covid-19 infected mothers in the 3rd trimester or intrapartum.

METHODS

This was a retrospective cohort study conducted between the 28th of January 2021 and the 31st of June of the same year at Saint George University Medical Hospital, Beirut-Lebanon. All pregnant women, whether symptomatic or not, were tested for Covid-19 infection via PCR upon presentation for delivery. We randomly collected placentas from Covid-19 uncomplicated gestations and 3rd trimester or intrapartum Covid-19 infected mothers after obtaining an informed consent. Our control population included all previously healthy mothers, singleton, term, and uncomplicated pregnancies regardless of the mode of delivery during the same period of the study. The Covid- 19 infected group had similar medical and obstetrical background only for coronavirus infection during the 3rd trimester or upon admission. Placentas of the two groups were grossly and histologically examined by a single pathologist who was blinded to the placentas of each group. Examination was based on the Amsterdam Consensus Statement guidelines.

RESULTS

A total of 22 Covid-19 positive cases and 21 Covid-19 negative cases were included. The results showed no statistical significance for any of the placental pathologies including maternal vascular malperfusion, amniotic fluid infection including maternal response and fetal response, villitis of unknown etiology, intervillositis and chorangiosis and fetal vascular malperfusion, except for the vascular ectasia, were 5 cases were identified in the Covid-19 positive group (p < 0.05).

CONCLUSION

Covid-19 infection during the 3rd trimester of pregnancy is not a risk factor for the development of placental histopathologies.