Scientists analyzed 12 placentas of healthy women with pregnancies between 5 and 36 weeks. They found that placental cells that can be infected with SARS-Cov-2 have ACE2 receptors that the pathogen uses as a gateway to enter the body. This means that this organ can not only become infected, but also spread the virus locally.
However, it was also found that in late pregnancy, ACE2 are located on the cells in such a way that the virus circulating in the mother’s blood cannot affect them. This will most likely prevent infection of the placenta. The authors of the study noted that such a protective effect was rarely observed in the first trimester, therefore, intrauterine transmission is more likely to occur precisely in the early stages of pregnancy.
“As more pregnant women recover from SARS-CoV-2 infection in the first trimester, it is important to remain vigilant for possible placental infection and transmission of the virus from mother to fetus,” the study authors said. Scientists added that the effect of coronavirus on the fetus and newborn has not yet been studied.
Previously, the same group of scientists estimated the likelihood of transmission of the virus from a pregnant woman to her fetus. The study involved 127 women with pregnancy in the third trimester, 64 expectant mothers were confirmed to have COVID-19. But at the same time, none of the virus was found in the blood, including the umbilical cord. Scientists believe that it is the absence of the pathogen in the mother’s blood that can block the transmission of the pathogen to the unborn child.
However, in an earlier study in France, the risk of intrauterine transmission was not so small. Doctors analyzed 176 reported cases of neonatal coronavirus infection and found that approximately approximately children had become infected in the womb. The rest of the babies were infected in the hospital or from family members.