Being infected with the coronavirus during pregnancy can have negative consequences for the health of the mother and the baby, as studies have shown that pregnant women are more at risk of severe COVID-19, and also more likely to experience further complications. of pregnancy such as pre-eclampsia, having a premature delivery, or the death of the fetus.
New research led by the US National Institutes of Health (NIH) – NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) – has found that SARS-CoV-2 infection during pregnancy it can induce inflammatory immune responses in the fetus, even though the virus does not infect the placenta. The paper authors have identified unique maternal, fetal, and placental immune responses among pregnant women with COVID-19.
The results of the study, which have been published in Nature Communications, show the changes produced by the infection in the antibodies, the types of immune cells and the inflammatory markers in the blood of the pregnant woman, the blood of the umbilical cord and the tissues of the placenta.
How COVID-19 behaves during pregnancy
The researchers tested 23 pregnant women, 12 of whom tested positive for SARS-CoV-2; Of these, eight were asymptomatic, one had mild COVID-19 symptoms, and three had severe illness. After delivery, these scientists compared immune responses between mothers and their babies by comparing maternal blood and umbilical cord blood.
Altered immune activity was found in the placenta and umbilical cord blood of newborns of infected mothers
They observed inflammatory immune responses triggered by the virus in the women, their newborns, and placental tissues, regardless of whether the mothers had COVID symptoms. The authors of the work have described their main findings:
- In pregnant women infected with the coronavirus, there was a decrease in T cells, a type of immune cell that enhances antiviral responses.
- Mothers with SARS-CoV-2 infection developed antibodies against the virus, whether or not they had symptoms, and some of these antibodies were found in umbilical cord blood.
- Infected mothers had higher levels of markers of immune activity in their blood — cytokines — regardless of symptoms. The elevated cytokines are interleukin-8, interleukin-15, and interleukin-10.
- Babies whose mothers were infected, even those without symptoms, showed an inflammatory response that resulted in higher levels of interleukin-8, an increase that was seen despite the fact that the fetus presumably did not have COVID-19.
- Although SARS-CoV-2 was absent in the placentas, placentas from infected mothers had altered ratios of immune cell types. And altered immune activity (measured by changes in RNA transcripts) was also found in the placenta and umbilical cord blood of newborns of infected mothers. This indicates that the neonatal immune system is affected by maternal SARS-CoV-2 infection, even if the virus is not detected in the placenta.
The study findings, although it is a very small population sample, can help scientists better understand how COVID-19 behaves during pregnancy. The authors indicate that the key fact is that SARS-CoV-2 infection of the mother induces an immune response in the fetus even though the placenta has not been infected and the newborn has no symptoms. Therefore, it is necessary to investigate the possible long-term effects of this inflammatory process in the children of women who have contracted the infection during pregnancy.
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