Researchers from Vall d'Hebron University Hospital, CLÍNIC-IDIBAPS and Parc Taulí in Sabadell have demonstrated the damage caused by SARS-CoV-2 infection to the placentas of pregnant women. Specifically, they have verified the lethal effect on fetuses caused by COVID-19 in a group of pregnant women between 24 and 39 years old. Dr. Marta Garrido, Dr. Jéssica Camacho and Dr. Alexandra Navarro, pathologists from the Anatomic Pathology Service of the Vall d'Hebron University Hospital, participated in the study. The work, led by Dr. Alfonso Nadal, from the Anatomic Pathology Service of the Hospital Clinic and member of the Inflammatory Molecular Pathology and Solid Tumors group of the August Pi i Sunyer Biomedical Research Institute (IDIBAPS), has also involved Dr. Juan Carlos Ferreres, from the Parc Taulí University Hospital, and professionals from the obstetrics and microbiology services of the three centers and has been recently published in the journal Modern Pathology.
The study analyzes nearly 200 cases of pregnant women who were infected by COVID-19 during pregnancy, from the three hospitals. In total, 9 cases of SARS-CoV-2 infected placenta were demonstrated, 5 of which involved intrauterine fetal death. All the cases that were analyzed had a normal pregnancy and no other causes were identified that could lead to fetal death. Fortunately, placental involvement is very infrequent (4.5% of pregnant women who have suffered COVID-19, according to this series), and fetal deaths attributable to this involvement are only around 2.5%. The participation of Vall d'Hebron University Hospital in its role as a reference center for gestational COVID-19 has been key in this work to provide power to this research.
The study shows that infection of placental tissue is accompanied by a characteristic lesion consisting of necrosis of the trophoblast, a layer of cells that provides nutrients from the mother to the fetus inside the uterus, and collapse of the intervillous space, i.e. each of the cavernous spaces of the placenta located between the chorionic villi and occupied by maternal blood. This damage to the trophoblast points to a new complication of COVID-19. This involvement explains why the placenta is no longer spongy, is much harder and is damaged to the point of causing, in some cases, fetal death.
The placenta is the first organ to be formed in fetal development. It acts as the lungs, intestines, kidneys and liver of the fetus, obtaining oxygen and nutrients from the mother's blood supply. It is also responsible for many of the hormonal changes within the mother's body.
The pathologists of the study state that "the study evidences the damage caused by COVID-19 to the placenta. We had never seen these lesions in such damaged placentas before and there were no references because this is a new disease".