Pregnant women who have COVID are more likely to experience complications such as premature birth than expectant mothers who do not test positive for the virus, according to a study published on Friday.

Additionally, the infection could also see a three-fold risk of severe medical complications in newborns, University of Oxford scientists have discovered.

The study involved more than 2,100 pregnant women in 43 maternity hospitals in 18 low, middle and high-income countries worldwide.

Its findings link COVID to a higher risk of severe maternal and newborn complications than previously recognised.

"Women with COVID-19 during pregnancy were over 50 per cent more likely to experience pregnancy complications, such as premature birth, pre-eclampsia, admission to intensive care and death, compared to pregnant women unaffected by COVID-19," Aris Papageorghiou, Professor of Fetal Medicine at the University of Oxford, said.

"Newborns of infected women were also nearly three times more at risk of severe medical complications, such as admission to a Neonatal Intensive Care Unit – mostly due to premature birth. The good news, however, is that the risks in symptomless infected women and non-infected women were similar."

While there were very few maternal deaths during the study, the risk of dying during pregnancy and in the postnatal period was 22 times higher in women with COVID-19 than in the non-infected pregnant women.

The study also highlighted that close to 10 per cent of newborns from mothers that tested positive for the virus also tested positive for the virus during the first few postnatal days.