New York, Jul 11 (IANS): Covid-19 can be transmitted in the womb, say researchers after a case study provides evidence of intrauterine (in the womb) transmission of the novel coronavirus from mother to infant.

A US baby girl born prematurely to a mother with Covid-19 is the strongest evidence to date that intrauterine transmission of (SARS-CoV-2) can occur, the findings published in the Pediatric Infectious Disease Journal reported.

"Our study is the first to document intrauterine transmission of the infection during pregnancy, based on immunohistochemical and ultrastructural evidence of SARS-CoV-2 infection in the fetal cells of the placenta," said study lead author Amanda S Evans from the University of Texas Southwestern Medical Centre in the US.

The authors report on an infant delivered to a mother diagnosed with Covid-19, who also had type 2 diabetes. The infant was born at 34 weeks' gestation after the mother had premature rupture of the membranes.

The baby was born "large for gestational age" (LGA) - an important complication in infants of diabetic mothers. She was treated in the neonatal ICU due to prematurity and possible coronavirus exposure.

The infant appeared initially healthy, with normal breathing and other vital signs. On the second day of life, she developed a fever and relatively mild breathing problems.

"It is unlikely that the respiratory distress observed in this infant was due to prematurity since it did not start until the second day of life," the researchers wrote.

The study showed that the baby tested positive for Covid-19 infection at 24 and 48 hours after birth.

She was treated with supplemental oxygen for several days but did not need mechanical ventilation. Covid-19 tests remained positive for up to 14 days. At 21 days, the mother and infant were sent home in good condition, the researchers said.

The researchers examined the placenta, which showed signs of tissue inflammation.

In addition, specialised tests documented the presence of coronavirus particles as well as a protein (SARS-CoV-2 nucleocapsid protein) specific for the COVID-19 virus in fetal cells of the placenta.

Together, these findings confirmed that the infection was transmitted in the womb, rather than during or after birth.

"We wanted to be very careful of our interpretation of this data, but now is an even more important time for pregnant women to protect themselves from COVID-19," Evans noted.