High viral SARS-CoV-2 load in placenta of patients with hypertensive disorders after COVID-19 during pregnancy

FABRE, M.; CALVO, P.; RUIZ-MARTINEZ, S.; PERAN, M.; OROS, D.; MEDEL, A.; STRUNK, M.; BENITO, R.; SCHOORLEMMER, J.; PAULES, C.

Introduction: Studies described an increased frequency of hypertensive disorders of pregnancy after a COVID-19 episode. There is limited evidence about SARS-CoV-2 viral load in placenta. This study aimed to investigate the relationship between SARS-CoV-2 viral load in placenta and clinical development of HDP after COVID-19 throughout different periods of gestation. Methods: This was a case-control study in women with and without gestational hypertensive disorders (HDP) after SARS-CoV-2 infection diagnosed by RT-PCR during pregnancy. Patients were matched by gestational age at the moment of COVID-19 diagnosis. We performed an analysis of SARS-CoV-2 RNA levels in placenta. Results: A total of 28 women were enrolled. Sixteen patients were diagnosed with COVID-19 during the third trimester and the remaining twelve patients in the others trimesters. Ten placentas (35.7%) were positive for SARS-CoV-2, nine of them (90%) belonged to the HDP group versus one (10%) in control group (p=0.009). Those cases with the highest loads of viral RNA developed severe-preeclampsia. Conclusion: The presence of SARS-CoV-2 was more frequent in placentas of patients with HDP after COVID-19. There seems to be a relationship between high viral load in the placenta and the development of hypertensive disorders. We found SARS-CoV-2 viral load in placenta after birth in mothers infected at the first half of pregnancy, but with negative nasopharyngeal RT-PCR at delivery. Our data suggest that SARS-CoV-2 infection during pregnancy could trigger gestational hypertensive disorders through placenta-related mechanisms.