Researchers led by the University of Oxford’s Nuffield Department of Population Health warned that although transmission of the virus to infants was uncommon and most women had “good outcomes,” the high proportion of infected women from black or minority backgrounds “needs urgent investigation and explanation.”
The latest study is based on data from the UK’s Obstetric Surveillance System, a national system established to study a range of rare disorders of pregnancy.
The researchers said that of 427 pregnant women admitted to hospital with Covid-19 between March 1 and April 14, more than half were from minority groups, including 25% who were Asian and 22% who were black.
Most of the women were in their late second or third trimester, 70% were overweight or obese, 40% were aged 35 or over, and a third had pre-existing conditions, the researchers said.
Twelve babies born to mothers in the study tested positive for coronavirus, six of them within the first 12 hours of their lives.
UK Health Secretary Matt Hancock has warned that being black or from a ethnic minority background was a “major” Covid-19 risk factor.
In an address to parliament last week, Hancock said there was “much more work to do to understand the key drivers of these disparities, the relationships between the different risk factors and what we can do to close the gap.”
Public Health England’s analysis found that the link between ethnicity and health was “complex and likely to be the result of a combination of factors.”
“Firstly, people of BAME [black and minority ethnic] communities are likely to be at increased risk of acquiring the infection,” the government review said, noting that minorities are more likely to live in urban areas, in overcrowded households, in deprived areas, and have jobs that expose them to higher risk.
“People of BAME groups are also more likely than people of white British ethnicity to be born abroad, which means they may face additional barriers in accessing services that are created by, for example, cultural and language differences,” it added.
The groups are “also likely to be at increased risk of poorer outcomes once they acquire the infection,” the agency’s report found.
CNN’s Zamira Rahim contributed to this report.