Oxford University scientists said on Tuesday they would evaluate the effects of new coronavirus variants on pregnant women and newborns, as well as COVID-19 vaccination effects on complications during pregnancy and after birth.

The study comes less than a year after the university found that pregnant women with COVID-19 and their newborn children faced higher risks of complications, such as premature birth and organ failure risk, than was previously known.

The researchers said the study aimed to fill gaps, including the effects of new variants of the virus such as Omicron in a high-risk group that has seen "alarmingly" low rates of vaccination.

"The effects of COVID-19 in pregnancy have been underestimated and insufficiently studied," said Oxford University professor José Villar, who is also the co-lead of the study.

"Pregnant women were not even included in vaccine trials, which has allowed unscientific, scary 'information' to be widely disseminated."

Many global health authorities have said vaccinations during pregnancy is safe, with a US study last month finding that they were not associated with preterm delivery or underweight newborns.

In November, data from the UK Health Security Agency showed that COVID-19 vaccination was safe for pregnant women and not associated with higher rates of complications.

The upcoming British study will enroll about 1,500 women who have tested positive for the virus at any stage of pregnancy and compare them with 3,000 non-infected women over four months. Oxford scientists said they expect the trial's results in May.