New York, May 23 (IANS): The placentas from 16 women who tested positive for Covid-19 while pregnant showed evidence of injury, the organ that acts as the gut, kidneys, liver and lungs for a fetus during pregnancy, say researchers.

According to the study, published in the American Journal of Clinical Pathology, pathological exams completed directly following birth found evidence of insufficient blood flow from the mother to the fetus and blood clots in the placenta. The type of injury seen in the placentas shows abnormal blood flow between the mothers and their babies in utero, pointing to a new complication of Covid-19. The findings could help inform how pregnant women should be clinically monitored during the pandemic.

"Most of these babies were delivered full-term after otherwise normal pregnancies, so you wouldn't expect to find anything wrong with the placentas, but this virus appears to be inducing some injury in the placenta," said study senior author Dr Jeffrey Goldstein, assistant professor of pathology at Northwestern University in the US.

"Not to paint a scary picture, but these findings worry me," said study researcher Emily Miller.

"This preliminary glimpse into how Covid-19 might cause changes in the placenta carries some pretty significant implications for the health of a pregnancy. We must discuss whether we should change how we monitor pregnant women right now," Miller stressed.

According to the researchers, examining a woman's placenta allows a pathologist to follow a retroactive roadmap of a woman's pregnancy to learn what happened to the baby in utero or what could happen to both the mother and the infant after birth.

"The placenta acts as a ventilator for the fetus, and if it gets damaged, there can be dire outcomes," Miller said.

"In this very limited study, these findings provide some signs that the ventilator might not work as well for as long as we'd like it to if the mother tests positive for SARS-CoV2," Miller added.

The placentas in these patients had two common abnormalities: insufficient blood flow from the mother to the fetus with abnormal blood vessels called maternal vascular malperfusion (MVM) and blood clots in the placenta, called intervillous thrombi.

"Our finding support that there might be something clot-forming about coronavirus, and it's happening in the placenta," Goldstein added.

The 16 women in the study delivered their babies at Northwestern Medicine Prentice Women's Hospital. All tested positive for Covid-19. Four patients came in with flu-like symptoms three to five weeks before delivery and tested positive for the virus. The remaining patients all tested positive when they came in to deliver.

Five patients never developed symptoms, others were symptomatic at delivery. The team began testing placentas of Covid-19 positive mothers in early April. "They were healthy, full-term, beautifully normal babies, but our findings indicate a lot of the blood flow was blocked off and many of the placentas were smaller than they should have been," Miller said.

"Placentas get built with an enormous amount of redundancy. Even with only half of it working, babies are often completely fine. Still, while most babies will be fine, there's a risk that some pregnancies could be compromised," Miller noted.