Three babies in China may have contracted new coronavirus in the womb shortly before birth, according to two new reports.
However, experts argue that the evidence in these cases is inconclusive and does not prove that the new coronavirus, SARS-CoV-2, can pass from mother to child during pregnancy.
In a report, doctors at Renmin Hospital in Wuhan University in Wuhan, China, describe the case of a woman who gave birth several weeks after being hospitalized for COVID-19, the disease caused by the new coronavirus. The little girl was delivered by Cesarean, and mother was wearing an N95 mask and was not holding the child, according to the report published today (March 26) in the newspaper JAMA. The newborn was immediately quarantined, but showed no symptoms.
Two hours after birth, tests have shown that the baby has high levels of two types of antibodies to SARS-CoV-2. These antibodies are called IgG and IgM. Although IgG antibodies are known to pass from mother to child during pregnancy, IgM antibodies are too large to cross the placenta, according to one editorial accompanying the report. Thus, “detection in a newborn baby could reasonably be assumed to reflect fetal production following an in utero infection,” said the editorial.
The child also had increased levels of immune system chemicals called cytokines, as well as white blood cells, which may be signs of infection.
But critically, the baby has repeatedly tested negative for the SARS-CoV-2 virus itself. This means that it is not clear whether the baby has already been really infected with the virus, or whether there could be another explanation for the positive IgM result.
In a second report, also published in JAMA on March 26, doctors from Wuhan University’s Zhongnan Hospital analyzed blood samples from six newborn babies for antibodies to SARS-CoV-2. They discovered that five infants had high levels of IgG and two infants had high levels of IgM, like the baby in the first report. However, none of these infants tested positive for SARS-CoV-2.
An additional explanation for SARS-CoV-2 infection could be that the mothers’ placentas were damaged or abnormal in some way, allowing IgM antibodies to cross the placenta to infants, wrote the authors of Zhongnan Hospital.
It is also important to note that IgM tests can be subject to false positive and false negative results, and are generally not used to diagnose infections acquired in utero, according to the editorial.
“Although these two studies deserve careful evaluation, more definitive evidence is needed before the provocative results they report can be used to advise pregnant women that their fetuses are at risk of congenital SARS-CoV- infection. 2 “, concludes the editorial.
Earlier this month, a baby in London tested positive for SARS-CoV-2 minutes after being born to a mother with COVID-19, Live Science had previously reported. However, in this case, it is still not known whether the virus passed to the infant during or immediately after birth.
In addition, a preliminary study of nine pregnant women with COVID-19 Live Science has not reported any evidence of mother-to-child transmission of SARS-CoV-2 in the womb.
Originally posted on Live Science.