There is no evidence that mothers recently infected with coronavirus, pass it on to their babies through breastfeeding, according to a new small American scientific study. The study found that although a low proportion of breast milk contains genetic material of coronavirus, this does not «translate» into the presence of infectious virus particles that can replicate or into Covid-19 infection in breastfed babies.
The researchers, led by Dr Paul Crogstad of the University of California, who published the paper in the paediatric journal Pediatric Research, analysed breast milk samples from 110 breastfeeding mothers, 65 of whom had previously tested positive for coronavirus, nine of whom had suspicious symptoms but tested negative and the rest of whom also had symptoms but had not tested positive.
Coronavirus RNA was detected in the breast milk of seven women (6%), while a second sample taken from the same mothers days later no longer detected the virus RNA. However, the scientists found no evidence of the presence of infectious coronavirus or clinical evidence of Covid-19 infection in the infants of the seven women.
The researchers noted that their study sample was relatively small, although it is the largest study to date that analyses breast milk and concludes that breastfeeding by mothers with diagnosed or suspected coronavirus does not lead to Covid-19 infection in their babies.
«Breast milk is a valuable source of nutrition for infants. In our study, we found no evidence that the milk of a mother infected with Covid-19 contains infectious genetic material, nor any clinical evidence that the babies themselves are infected, suggesting that breastfeeding is unlikely to pose a risk,» said Crogstad. In other words, breastfeeding mothers with Covid-19 infection do not pose a risk to their babies.
Another small US study by the US National Institute of Child Health and Human Development (NICHD), published in the journal Nature Communications, shows that infecting a pregnant woman with coronavirus can cause an inflammatory immune response in the foetus, even if the virus has not infected the placenta.
Pregnant women are more at risk of severe Covid-19 compared to non-pregnant women. Covid-19 during pregnancy also increases the risk of preterm delivery, stillbirth and pre-eclampsia.
The new study looked at 23 pregnant women, 12 of whom had coronavirus (eight with no symptoms, one with mild symptoms and three with severe symptoms). The scientists' key findings were as follows:
Pregnant women with coronavirus have fewer immune system T-lymphocytes, hence lower defence against the virus.
Mothers with coronavirus develop antibodies against the virus whether they have symptoms or not, and some of these antibodies are detected in the cord blood.
Mothers with coronavirus have a higher level of inflammation and immune response markers in their blood, regardless of their symptoms (the elevated cytokines are interleukins 8, 10 and 15).
Babies from coronavirus-infected mothers (even asymptomatic ones) have higher levels of interleukin-8, even if they do not have Covid-19.
While coronavirus is not detected in the placenta, the placentas of mothers with coronavirus have a different «profile» of immune cells, an indication that the baby's immune system is affected by maternal Covid-19 infection, even if the virus is not present in the placenta.
