According to a study by Weill Cornell Medicine and New York-Presbyterian researchers, SARS-CoV-2 infections in women at the end of pregnancy frequently spread to their placentas and caused inflammation. The findings suggest that more research is needed on the effects of the virus during pregnancy and underscores the current U.S. Centers for Disease Control and Prevention recommendation that pregnant women continue to take precautions, such as masking, distancing social and vaccination, to reduce their risk of suffering. SARS-CoV-2 infection.
In the study, published April 11 in iScience, researchers found signs of SARS-Cov-2 infection, inflammation and tissue damage in 22 of the placentas of 52 mothers who tested positive for the virus in the time of delivery in New York-Presbyterian. Weill Cornell Medical Center. The researchers also found in laboratory studies that newer variants of SARS-CoV-2, including the Delta variant, were more likely to infect placental tissue than the original strain.
The main message of these findings is that placental infection can occur with SARS-CoV-2 and can cause severe inflammatory responses in the placenta, and this raises questions about the short- and long-term effects in newborns. “
Dr. Heidi Stuhlmann, Senior Co-Author, Professor and Acting Professor of Cell and Developmental Biology and Biochemistry, and Harvey Klein Professor of Biomedical Sciences at Weill Cornell Medicine.
The study was a collaboration that also included the laboratories of Dr. Robert Schwartz, Associate Professor of Medicine in the Division of Gastroenterology and Hepatology, and Dr. Shuibing Chen, Professor of Kilts Family Surgery, at Weill Cornell Medicine. The co-authors are Lissenya Argueta, a graduate student at Stuhlmann Laboratory, Dr. Lauretta Lacko, a postdoctoral fellow in surgery at Chen Laboratory, and Dr. Yaron Bram, an associate researcher in medicine at Schwartz Laboratory.
Some viral infections are known to increase the risk of adverse labor outcomes and developmental disorders during pregnancy. Inflammation of the placenta due to infection is considered a possible mediator of these effects.
Although studies show that pregnant women with covid are at higher risk for certain complications of pregnancy, it is still unclear about the effects of SARS-CoV-2 during pregnancy. Major recent studies indicate that mothers infected with SARS-CoV-2 with moderate to severe symptoms are more likely to experience adverse events during pregnancy and postpartum, such as premature birth, postpartum hemorrhage, and an increased risk of stillbirth. or early neonatal death. In addition, transmission of the virus from infected mothers to their babies appears to be extremely rare.
To clarify these issues, the team studied the placenta, the organ that develops between the fetus and the mother to deliver nutrients, oxygen and hormones to the developing fetus, from a series of 52 pregnant women who tested positive for SARS-CoV-2 at the time they delivered.
The researchers found that significant placental abnormalities were absent in four control placentas of uninfected mothers, but were present in most placentas of infected mothers: 33 of the 52 (64%) had potentially serious placental conditions known as fetal or maternal vascular malformation. vascular malformation, affecting maternal blood flow to the fetus, or both.
In addition, although no newborn tested positive, 22 of the 52 placentas (42%) tested positive for SARS-CoV-2 genetic material. Two of these placentas had very high levels of the Alpha variant virus: one was associated with stillbirth, the other with the prematurely severe birth that required prolonged intensive care.
Examination by researchers of the two most highly infected placentas revealed a significant infiltration of maternal immune cells, as well as signs of inflammatory damage to placental tissue, which probably contributed to the adverse outcomes of childbirth.
Finally, researchers demonstrated in laboratory experiments that placental cells that are in contact with maternal blood can become infected with SARS-CoV-2. They also showed that newer variants of the virus, including the Delta variant, the study concluded just before the Omicron wave, were generally more able to infect placental tissue, compared to the original virus.
Researchers have continued with more studies, including placentas infected during the Omicron wave.
“The evidence we’ve gathered so far supports the idea that newer variants are better not only for infecting mothers, but also for infecting the placentas,” Dr. Chen said.
The team hopes to conduct long-term studies on health outcomes among children born to mothers infected with SARS-CoV-2.
“To address the issue of long-term impacts, we need to establish large cohort studies that follow children born to mothers with SARS-CoV-2 for years,” said Dr. Schwartz, who is also a New York-Presbyterian hepatologist. Weill Cornell Medical Center.
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Magazine reference:
Argueta, LB, et al. (2022) Inflammatory responses of the placenta to SARS-CoV-2 infection at the end of pregnancy. iScience. doi.org/10.1016/j.isci.2022.104223.