Pregnant women who catch Covid may pass on the virus to their babies as some infants test positive within hours of birth, study shows

 Some babies develop COVID-19 within hours of their birth, but it's not yet clear if the deadly virus was passed on during pregnancy.

A University of NSW-led review of existing COVID-19 infection data found five out of 139 newborns from infected mothers were diagnosed within several hours or just days after birth.

But confirming COVID-19 transmission from mother to newborn is difficult to verify and further research is needed to find out, senior study author Dr Nusrat Homaira of UNSW said in a statement on Wednesday.

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Some babies develop COVID-19 within hours of their birth, but it's not yet clear if the deadly virus was passed on during pregnancy (stock)

'More research is needed to understand if children born to women who have Covid-19 during pregnancy have an increased risk of acquiring the infection and what the long-term outcomes are for newborns with the disease,' she said.

The findings could influence Australia's plans to vaccinate the population against the deadly disease in terms of vaccinating young children and mums-to-be.

'As the vaccine is being rolled out to the whole population and other parts of the world, maternal immunisation could be a viable preventive approach,' Dr Homaira said.

The UNSW team examined a range of international COVID-19 research, particularly in relation to children under five years of age.

An examination of 1,214 cases of Covid-infected children in the 65 studies from 11 countries found half were infants and half of the total were asymptomatic. All but one recovered.

This group is most at risk of respiratory infections, which are one of the most common reasons children end up in hospital.

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The UNSW team examined a range of international COVID-19 research, particularly in relation to children under five years of age (Pictured: Healthcare worker at Royal Melbourne Showgrounds)

'Children often have asymptomatic infection, generally, and play a significant role in transmission of respiratory infections within the community,' Dr Homaira said.

That's why immunisation programs often target the under-five age group for infections like the flu.

'So, we wanted to understand all those issues in light of Covid-19,' Dr Homaira added.

The research aligns with other studies showing more than 90 per cent of children develop mild to moderate cases of Covid-19 when infected.

The review, the first to specifically examine the under-five age group, was published in The Lancet Journal of Child and Adolescent Health in August.